Hyde Park demonstration is expected to draw the biggest crowds since VE Day

The Rev Jesse Jackson, who will headline next week's anti-war demonstration in Hyde Park, London, said yesterday that the eyes of the world would be on the people of Britain in the hope that they could help to avert a military assault on Iraq.

Organisers expect Saturday's march to be the biggest demonstration in British history, drawing the largest assembled crowd on to the streets of London since VE Day.

Mr Jackson, a veteran civil and human rights campaigner, said he had decided to speak in London, rather than at similar rallies in New York or San Francisco, because he believed public opinion in Britain could prove to be more crucial.

Speaking exclusively to The Independent on Sunday, he said: "I think the people of Britain must pressure [Tony Blair]. He has dug his heels in, but in a democracy while leaders speak, people speak louder and people over the world are impressed by the demonstrations of the people of London. It was the same with the demonstrations in London over the freeing of Nelson Mandela. They have left a very powerful impression on people around the world. There is no future in war. The [London] marchers help the chance of people. The [world] will be looking at them."

Mr Jackson, 63, also made a direct challenge to Mr Blair, urging him to visit Iraq and confront Saddam Hussein in person. He said that the Prime Minister's role in finding a peaceful solution was "critical" and he asked him to "use his talents" to do so.

"It would be daring if he went to Iraq, for example," said Mr Jackson, who himself visited Saddam in 1991 to secure the release of hostages held by Iraqi forces in Kuwait prior to the start of the Gulf war. "He has nothing to lose but lives, and nothing to gain but peace and economic growth if he is bold. He would be a strong factor [in preventing a war]. President Bush is leaning upon him heavily."

Mr Jackson, president of the Rainbow/Push Coalition, which campaigns on behalf of the "disadvantaged and people of colour", has also urged Saddam to act.

In an open letter to the Iraqi leader, Mr Jackson asks him to hand over any weapons of mass destruction he has immediately. He says Iraq's "arsenal offers you no protection; instead it is a clear and present threat to you and your country".

He adds: "Once more, I call on you with our countries on the verge of war, just as I did 12 years ago. Once more, we face a war of terrible consequence. Once more, I appeal to you to act now to avoid the impending catastrophe."

His letter ends with the words: "Once more the fate of your country lies in your hands. I beseech you to act now, boldly, destroy your weapons to avoid a catastrophic war."

Because of the expected size of Saturday's demonstration, two separate route marches have been drawn up, converging in Piccadilly and ending in Hyde Park. One will begin on the Embankment, near Blackfriars station. Marchers travelling from the north are being urged to assemble in Gower Street, near Euston Square station.

To encourage protesters to arrive in London early, the Stop the War Coalition has organised a series of events on Friday, beginning with a meeting of Poets against the War at the South Bank at 6pm.

Rob Glanz, 45, Psychotherapist from London

"The Government needs to be impressed about the groundswell of opinion against going to war. The case hasn't been proven. It's a breakdown of international law to go to war without a UN mandate."

Matt McGuire, 14, Schoolboy from Bournemouth, first protest march

"It's unfair that the big controlling countries are going to kill innocent people. If Saddam Hussein is a tyrant then we should find another way of getting rid of him."

Bianca Jagger, 57, Humanitarian campaigner living in London

"I do not believe Bush and Blair have made the case that Iraq presents an imminent threat to the US or Britain. It will not be a just war. Many Iraqis will be killed, but also Britons and Americans."

Sam Beste, 16, Sixth-former

"I hope there will be 100 people from my school on the march. The vast majority don't believe there's sufficient evidence to go to war. The idea you can attack a country because of something it might do sets a crazy precedent."

Sally Borchardt, 55, Lives near Evesham, Worcestershire

"I don't believe the case has been made. This just shows how much the Government runs by spin. America is not a country whose foreign policy judgements I hold in high esteem."

Jeremy Troxler, 25, Methodist minister from Jersey

"It comes down to the convictions of my Christian faith. This focus is so much on our own security. The greatest weapon of mass destruction is Aids in Africa. I wonder where our priorities are."

Richard Searle, 39, Homelessness case worker for Manchester City Council

"War already scares the living daylights out of me. I can't imagine what it's like for people in Baghdad. Blair's giving people lessons in the politics of oil and the Middle East."

Lara Frankel, 26, Singer from Hertfordshire

"Being Jewish and having lived in Israel, I have seen the devastation that war can cause. Bombing Iraq amounts to government-led terrorism. We shouldn't just sit back and let this happen."

Caelin Meredith, 25, Account manager from Canada living in London for a year

"I'm hardly what you'd call a seasoned activist. When I came to London, protesting for peace wasn't exactly on my agenda, but I now feel impassioned to get involved.

"I heard there might be 500,000 people there, so I believe we might have a chance to stop this war. We can't throw that away because the repercussions are not worth thinking about.

"As far as I can tell, the main reason for all this is that Saddam Hussein is guilty of possessing weapons of mass destruction. In that case, 80 per cent of the Western world is also guilty."

Interviews by Nicholas Pyke, Andrew Johnson and Caroline Ryder