George Galloway has said the assassination of Tony Blair would be "morally justified" given his support for the war in Iraq.
The anti-war Respect MP said a suicide bomb attack on the prime minister would be "morally equivalent to ordering the deaths of thousands of innocent people in Iraq as Blair did".
The controversial leftwinger added that he was not calling for such an attack and that he would tip off the authorities if he knew of one.
But his remarks provoked a furious response, with one Labour MP calling him "disgraceful" and "twisted".
In an interview for GQ magazine with the former editor of the Daily Mirror, Piers Morgan, Mr Galloway was asked whether the assassination of Mr Blair by a suicide bomber would be justified, if there were no other casualties.
He replied: "Yes, it would be morally justified. I am not calling for it, but if it happened I believe it would be of a wholly different moral order to the events of 7/7.
"It would be entirely logical and explicable. And morally equivalent to ordering the deaths of thousands of innocent people in Iraq as Blair did."
In response to the furore his comments have caused, Mr Galloway said: "Like the prime minister's wife commenting on suicide bombings in Israel, I understand why such desperate acts take place and why those involved might believe such actions are morally justifiable.
"From the point of view of someone who has seen their country invaded and their family blown apart it's possible, of course, for them to construct a moral justification. But I've made my position clear. I would not support anyone seeking to assassinate the prime minister. That's why I said in the interview I would report to the authorities any such plot that I knew of.
"What I did make abundantly clear to Piers Morgan in the GQ interview is that I would like to see Tony Blair in front of a war crimes tribunal for sending this country to war illegally and for the appalling human consequences which resulted. That's what I will continue to press for," he said.
He added: "Such an operation would be counter-productive because it would just generate a new wave of anti-Arab sentiment whipped up by the press.
"It would lead to new draconian anti-terror laws, and would probably strengthen the resolve of the British and American services in Iraq rather than weaken it.
"So, yes, I would inform the authorities."
Mr Galloway has been MP for Bethnal Green and Bow in east London since he ousted sitting Labour MP Oona King in last year's general election on a strongly anti-war ticket.