Blix talks of Blair's 'impression of lack of sincerity'

Tony Blair may have lost the crucial Commons vote on the Iraq war if he had admitted at the time he wanted to depose Saddam Hussein regardless of whether he had weapons of mass destruction, a senior minister acknowledged yesterday.

The Defence Secretary Bob Ainsworth – who was deputy chief whip at the time of the vote in March 2003 – said he was surprised by Mr Blair's remarks, made in a BBC documentary, in which he said he believed it still would have been right to take military action even if it had been known at the time Saddam did not have WMD.

Mr Ainsworth said: "I don't know what the situation would have been if those arguments had been put differently. That is a parallel universe that didn't exist," he told the BBC1 Politics Show. "I supported the war in Iraq based on the arguments that were put at the time and a big part of those arguments was – and I firmly believed that they existed – was the existence of WMD at that time." Asked if he was surprised by Mr Blair's remarks, Mr Ainsworth replied: "A little bit." Asked if they were a mistake, he said: "I don't know."

Mr Blair is to give evidence to the official Chilcot Inquiry into the war in the new year. Tory leader David Cameron said it was essential as much as possible of his evidence was heard in public after claims that key elements would be held behind closed doors.

The Independent on Sunday reported that details of Mr Blair's discussions with President George Bush would be dealt with in private for reasons of national security and to protect Britain's relations with the US. "Tony Blair will need to answer for himself but I am sorry that all his evidence seems to be going to be carried in secret," Mr Cameron told Sky News's Sunday Live programme. "Some parts of his evidence perhaps should be in secret if they're going to reveal important national security points but I think a lot of it could be done in public and should be done in public."

But Hans Blix, who was in charge of the UN team searching Iraq for WMD, said he thought Mr Blair used WMD as a "convenient justification" for war. "Saddam's removal was a gain but it's the only gain that I can see from the war," he said, adding that Mr Blair's statement had a "strong impression of a lack of sincerity".

A spokesman for the Chilcot Inquiry insisted the former prime minister would face extensive questioning in public. "Mr Blair will be appearing very much in public and will be questioned in detail on a wide range of issues surrounding Britain's involvement in Iraq," he said. "We said right from the start that he will be a key figure in the inquiry. Mr Blair has said he is ready and willing to give evidence in public."

Under the procedures adopted by Sir John Chilcot, the retired Whitehall mandarin heading the inquiry, most evidence will be taken in public although there is a provision for closed hearings to cover issues concerning national security or secret intelligence.

So far, the only witness who will give evidence in private is Sir John Scarlett, the former MI6 chief and chairman of the Joint Intelligence Committee, who drew up the Government's controversial Iraq dossier and who appeared in public last week.

It is believed no decision has been taken on a closed session with Mr Blair.