Former prime minister John Major said Saturday that the Iraq war inquiry appeared to be showing that the invasion was more about regime change than finding weapons of mass destruction.
Criticising his successor Tony Blair over his presentation of the case for invading, Major told BBC radio that Iraqi dictator Saddam Hussain may have been a "bad man" -- but that was not a good enough reason to go to war.
He asked whether Blair's cabinet was aware of doubts about whether Iraq had weapons of mass destruction before deciding to take military action. Britain joined in the March 2003 US-led invasion.
"The suspicion arises that this was more about regime change than it was about weapons of mass destruction," Major said.
However, "the argument that Saddam Hussain was a bad man and therefore must be removed simply won't do," he added.
"There are many bad men around the world who run countries and we don't topple them and, indeed, in earlier years we had actually supported Saddam Hussein when he was fighting against Iran.
"The argument that someone is a bad man is an inadequate argument for war and certainly an inadequate and unacceptable argument for regime change."
Major, premier from 1990 to 1997, said he had trusted Blair's claims about the danger posed by Iraq.
"I supported the Iraq war because I believed what the prime minister said.
"I had myself been prime minister in the first Gulf War, and I knew when I said something I was utterly certain that it was correct, and I said less than I know," he said.
"I assumed the same thing had happened and on that basis I supported reluctantly the second Iraq war."
Blair is due to give evidence sometime in January or early February, alongside his former defence and foreign ministers, his government's then most senior lawyer and his former press chief.
Prime Minister Gordon Brown, who was Chancellor at the time of the invasion, is due to appear after the next general election, which must be held by June.
The long-awaited inquiry led by former senior civil servant John Chilcot was set up following the withdrawal of British troops from Iraq in July last year. Aimed at learning the lessons from the war, it is due to report by the end of 2010.