Malcolm Chisholm described the decision as "immoral"

The Labour MSP for Edinburgh North and Leith said he had put loyalty to his party colleagues before his personal views.

He described the decision as "immoral" and urged other people in the Labour Party to speak out against the war.

The Scottish Labour Party leadership narrowly prevented an embarrassing vote against the prime minister's stance following a tense debate called by the Scottish National Party on Thursday.

'Let myself down'

Six Labour MSPs rebelled against the party line and backed an amendment from party left-winger John McAllion insisting "no case for military action against Iraq has been proven".

A further three Labour backbenchers abstained on Mr McAllion's anti-war amendment although it was ultimately defeated with 57 votes for, 62 against and three abstentions.

Mr Chisholm said he had been troubled by his actions.

I think, on reflecting on it, what happened was that I put loyalty to my colleagues before what I knew to be right Health Minister Malcolm Chisholm

The minister said: "I certainly felt very uneasy over the last 36 hours, in fact I feel I let myself down very badly.

"I was going to vote with John McAllion until the last moment and I was prevailed upon not to.

"I think, on reflecting on it, what happened was that I put loyalty to my colleagues before what I knew to be right.

"And I think ultimately that is an immoral thing to do."

Mr Chisholm also said the case for war had not been proven and that he felt it was right to "speak out".

John McAlliion: Amendment

He urged other people in the Labour Party who felt strongly about the Iraq issue should to speak out against it as this could be their "last opportunity".

Scottish National Party campaign co-ordinator Nicola Sturgeon said Mr Chisholm will be tarnished with the "stain of complicity" despite his admission.

Ms Sturgeon said: "On Thursday, no-one was under any illusions. MSPs faced a straight choice - peace or war. Malcolm Chisholm voted for war.

"For him now to suffer an attack of conscience over his support for Bush and Blair is to be welcomed, but it will not remove the stain of complicity from the health minister."

She added: "The time to stand up and be counted was in the vote on Thursday. "Instead he has admitted he placed party loyalty ahead of what he knew to be right.