Charles Kennedy: So were we misled? We need a full-scale inquiry

In trying to make the case for war, Tony Blair stretched his credibility to the limit and has potentially done serious harm to his own standing and public trust in Government.

We must now have an independent inquiry by a special Select Committee of the House of Commons to investigate the alleged politicisation of intelligence. If Parliament was misled as to the nature and imminence of the threat from Iraqi weapons of mass destruction, this is extremely serious. Unfortunately, regardless of the truth, the damage has been done. The string of promises to sweeten the pill over Iraq, has already been broken.

Before the war, Mr Blair made a number of assertions. On Newsnight (6 February) he said he would not go to war without a second UN Security Council resolution unless the weapons inspectors concluded there had been no progress in the disarming of Iraq, or if there was an "unreasonable veto" from one permanent member AND a majority in favour in the Security Council. In fact, we went to war unilaterally with the Americans, with the weapons inspectors protesting they still had work to do and without the so-called second resolution even being put to a vote.

On 18 March, a doubtful House of Commons was persuaded to vote to endorse the war because "Iraq's weapons of mass destruction and long-range missiles ... pose a threat to international peace and security". Those were the grounds for military action. A number of reluctant Labour MPs were cajoled into voting in favour on the basis of trust in the Prime Minister.

Over the preceding months, Mr Blair built up his case, repeatedly asserting that Saddam Hussein possessed weapons of mass destruction. On 24 September he told the House of Commons that "his weapons of mass destruction regime is active, detailed and growing ... [Intelligence] concludes that Iraq has chemical and biological weapons, that Saddam has continued to produce them, that he has existing and active military plans for the use of chemical and biological weapons, which could be activated within 45 minutes".

Ministers have since said this information was uncorroborated. After the war, the Defence and Foreign secretaries have been at pains to play down previous claims. On 23 April, Geoff Hoon told BBC Radio 4's Today programme that Saddam's "weapons of mass destruction remained hidden as they are hidden to this day. He did not have the time to recover the weapons from those hiding places to reassemble the missiles and then to fire them". In other words, even if he had them, they were not and could not be fired within 45 minutes.

Jack Straw, meanwhile, was playing down claims that Saddam held up to 10,000 litres of anthrax. He told the BBC that "10,000 litres is one third of one petrol tanker. Whether or not we are able to find one third of one petrol tanker in a country twice the size of France, remains to be seen". Is this the same anthrax that threatened the security of the Western world?

The decision to go to war in Iraq was highly contentious and divisive. In Britain, as in other countries, many people were not convinced military action was necessary when the weapons inspectors had not been allowed to complete their task. It was a judgement call.

Tony Blair's decision to back the United States against British public opinion was not uncommonly brave or radical - it was the path of least resistance. I did not doubt the Prime Minister's sincerity as he argued his case. But the questions we asked before the war remain unanswered: where is the proof of this threat? Why did we need to abandon the United Nations inspection process with such urgency? Will military action really make the Middle East and the world a safer place?

We asked the Government to make its case for war. However, nothing changed between publication of the Government's dossier in September 2002, and the failure to secure a second UN resolution in March 2003, to change my mind.

The only thing that did change was the Government's arguments in favour of military action. As international alliances in Nato and the EU fractured, I became convinced that we had to secure a consensus before going to war.

In answer, sceptics were told to wait and see. Well, we are still waiting. Iraq has been under coalition command since 20 April. No weapons and no long-range missiles have been found so far. No Iraqi assembly has been formed and Iraqis and coalition soldiers continue to die almost every day.

There is nothing more precious in our public life than trust between the people and their elected representatives. Some of the most lingering collateral damage of this war may ultimately prove to be here at home.

The writer is leader of the Liberal Democrats.