The government's public justification for going to war with Iraq was an "uncertain fantasy", according to a minister serving in Tony Blair's administration at the time.
Michael Meacher was minister for the environment until last month
Michael Meacher, environment minister until last month's government reshuffle, said he was among those ministers and MPs who feel they were misled over the case for war.
In an interview with BBC News Online he said he had accepted at face value government claims that Saddam Hussein's regime possessed weapons of mass destruction because "I believed what the intelligence services and the government were saying."
"Tony Blair made speeches in which he said that with great categorical certainty, and who am I to disbelieve that?"
But the continuing absence of the discover of such weapons now showed that the case made by Prime Minister Tony Blair for war with Iraq was seriously flawed.
"The ostensible reason for going to war, the public reason, has turned out to be uncertain, unreal, fantasy - and we're still not absolutely sure what the intelligence services actually did say," Mr Meacher said.
The Oldham MP, who has also spoken out against government policy towards genetically modified (GM) foods in recent weeks, said he feared the lack of public trust over Mr Blair's arguments for war "radiates to every other aspect of government policy, including genetic modification - and I think the government's trustworthiness on this issue is quite low."
A Mori poll published in the Financial Times newspaper just this week found that almost two-thirds of the public did not trust the prime minister.
Later this year a government report is expected to clear the way for GM foods to be sold in supermarkets. Mr Meacher believes much more scientific research is necessary before such a decision can be made.
"We want more time for tests," he said. "That's a totally respectable, honest, frank and correct scientific position to take."