Tony Blair and his fellow G8 leaders will have to settle a transatlantic row over aid and trade that dominated the talks between their officials, known as "sherpas" at the weekend. The disagreement is over the prominence of the details of what individual member countries are pledging to give to the target of doubling the annual global aid budget to $100bn (£60bn) set by Mr Blair.

The European Union has committed to double its aid from $40bn last year to $80bn by 2010. The US has offered to add an extra $4.5bn while offers from Canada and Japan appear to take the total to $47bn.

However, it is understood the US has been "stung" by signs that the process had been turned into a "beauty contest" of aid pledges - with their $4.5bn looking somewhat flaccid alongside the EU's $40bn.

More progress was made at the weekend by the sherpas on the climate change communiqué about climate change. Mr Blair, in Singapore for the Olympic bid, said a deal was "within our grasp" but again the finger of blame is already pointing at the White House where the President's advisers could insist on US concessions being withdrawn.

On aid to Africa, the eight nations have not yet agreed what the headline sum should be as there is mounting concern that some of the contributions will be attacked by campaigners as reannouncements of old commitments. ActionAid, the global campaign group, said America's $4.5bn includes $3bn already in the pipeline from the Millennium Challenge Account. Groups are also worried that since the aid is specifically for Africa, the White House might raid its budget for other poor countries to pay for it.

The Make Poverty History Coalition, which is calling for $50bn of new aid to come on stream next year, said no money would be on stream in 2006 while just $8.5bn of the $25bn package specifically for Africa was actually new money. Steve Tibbett, ActionAid's head of policy and campaigns, said rich nations were using millions of poor people to "score a PR coup".

"Look behind the rhetoric and the reality falls far short," he said. "We are still nowhere near a deal that will effectively tackle global poverty. So far the UK Government is largely serving up spin and hype. "

Jo Leadbeater, head of advocacy at Oxfam, said: "This is the first time in history the text of the final communiqué has been up for grabs this late in the game."

She said that delaying aid increases until 2010 as proposed would leave a $100bn "black hole" in aid budgets and 500 million people in desperate poverty.

On climate change, there were signs the irritation by Jacques Chirac, the French President, with Mr Blair over CAP reform and the EU constitution has spilled into the G8 meeting. The French have been insisting on Mr Blair - as the host for the conference - engaging in tough bargaining with the US, including putting an explicit reference to Kyoto protocols in the communiqué. However, French officials made clear they never intended to scupper the talks with the US, which has refused to sign up to Kyoto.

America, meanwhile, moved towards the rest of the G8 by accepting some of the scientific arguments that mankind was responsible for the warming of the planet.

The French were also pleased that the communiqué negotiated by the sherpas contained references to the emissions trading which has been started in Europe. British officials said Mr Blair thought there was "a growing consensus" on the approach to greenhouse gases said to be causing global warming. "We are aware progress has been made and we still are making progress but we won't be able to see how far we have got until Thursday or Friday," said the Prime Minister's spokesman.

Referring specifically to climate change agreements, he added: "We still need to go down to the wire."

However, a spokesman for Friends of the Earth said: "It is worrying. All these negotiations seem to be going backwards.The communique is weak and nothing that George Bush has said has filled us with confidence at all."

The leaders

George Bush, United States

What he wants

Wants to be seen as the American president who has done the most for Africa. His administration has tripled aid to Africa since 2001, and plans to double the 2004 level to $8.6bn by 2010. Will fight anything other than voluntary measures to curb greenhouse gases.

What he'll get

The deals on debt and aid are already agreed, but there is likely to be criticism of the lack of new money from the US in the aid package. Could get his way on trade reform - he is refusing to tackle farm subsidies until Europe does.

The reality?

The US has spent billions on aid, but this represents only 0.17 per cent of national income, well down on the UN target of 0.7 per cent. Bush is also hamstrung by Congress on aid. On climate change, his loyalty to "big oil " undermines his statements about new technologies.

Tony Blair, United Kingdom

What he wants

Hopes to put Iraq behind him by rebranding himself as the saviour of Africa, thanks to aid and debt cancellation deals. Wants to give fresh impetus to global trade talks to benefit Africa. On global warming, hopes for increased investment in cleaner energy even without agreement on the science.

What he'll get

The aid and debt relief deals were pretty well sewn up before the summit, with agreement to cancel £25bn in debts for the 18 poorest countries, including 14 in Africa. Attention will focus on the new money in the aid pledges, while talks on trade and climate change will go to the wire.

The reality?

Aid agencies are already saying the summit will fall short of the response needed to tackle global poverty.

According to War on Want, the money on the table will provide less than 5 per cent of the debt relief and less than 20 per cent of the aid needed to meet the objectives of Make Poverty History.

Silvio Berlusconi, Italy

What he wants

Always aligns himself with Bush and Blair, and the G8 Summit will be no exception. So Berlusconi will support Blair's summit goals on Africa and climate change.

What he'll get

Will not be in trouble on summit issues: despite the success of the Rome Live8 concert, Africa is not a major domestic priority. Being seen in the company of Bush and the other G8 leaders could highlight his qualities as a statesman at a time when his popularity is in decline.

The reality?

Italy, now in recession, will find it tough to follow through on meeting the European and UN target on overseas development aid, and the Italian finance ministry has refused to agree the EU timetable.

Jacques Chirac, France

What he wants

Wants the summit to go beyond debt cancellation and aid. Will push for recognition of a French proposal for air levy as a way to finance development. He also wants to stick to the 2013 deadline for renegotiating EU farm subsidies. Wants references to Kyoto and scientific consensus on climate change.

What he'll get

Will probably have to yield to get compromise on climate change in the face of US opposition. Possible deal on airline ticket levy to free up funds, but negotiations will go to the wire.

The reality?

Other countries may not be in the mood to listen to Chirac, knowing that he has been humiliated politically at home by the rejection of the EU constitution. Relations with Blair, the G8 host, are at a low after Chirac's gaffe on the quality of British food and the bitter contest over hosting the 2012 Olympics.

Junichiro Koizumi, Japan

What he wants

Has told Blair Japan will double aid to Africa over next three years, and will also offer support on climate change, having hosted the Kyoto protocols. Will also raise issue of North Korea's suspect nuclear programme, and Japan's bid for permanent membership of UN Security Council.

What he'll get

North Korea will be mentioned in summit documents tomorrow. Koizumi is a major ally of George Bush - illustrated by his decision to send troops to war in Iraq - even at the cost of his own popularity, which has halved since he came to power four years ago.

The reality?

The G8 is not the appropriate forum for any decisions on UN reform, although it provides an opportunity to sound out partners on pressing issues not on the summit agenda.

Paul Martin, Canada

What he wants

Hopes to deflect pressure to isolate US by committing Canada to giving 0.7 per cent of GDP in foreign aid. Plans to act as mediator on climate change after announcing plan to spend billions over next seven years to meet its Kyoto targets. Will push for expansion of G8 to include China, India and Brazil.

What he'll get

No chance the club will agree to new members - there are already questions as to whether Russia should be there in the first place.

The reality?

Diplomatically, Canada punches below its economic weight but may have a role as honest broker because of solid record as donor country.

Vladimir Putin, Russia

What he wants

Is satisfied by the fact Russia is at the G8 table, demonstrating it " counts". Supports Blair on Africa and climate change, having ratified Kyoto, although both are low on his agenda. Expected to latch on to Africa debate to push for debt relief for poorer former Soviet states.

What he'll get

An opportunity to take part in the debate on energy security, which he wants to be top of his agenda. Will also be watching how Blair handles himself, with Putin preparing to host next year's G8 summit.

The reality?

Russia is unlikely to contribute much towards increased aid for Africa because of its own economic problems.

Gerhard Schröder, Germany

What he wants

Has agreed timetable of aid to Africa, but argues that the right government institutions need to be in place before a dramatic increase in aid would make sense. Don't expect major initiatives from lame duck leader, with his ruling Social Democrats in state of limbo awaiting elections in September.

What he'll get

The result of climate-change negotiations is too close to call. With the elections pending, Schroder will use this as a time to secure friendships with other G8 leaders, in particular Chirac and Putin.

The reality?

Like Italy, Germany has balked at the EU timetable for increasing aid to Africa, and may not be able to afford the agreed increases.