The UN Secretary General has dismissed allegations that France and Russia might have been willing to ease sanctions on Iraq in return for oil.
Mr Annan has recently said the war on Iraq was "illegal"
Kofi Annan told the Jonathan Dimbleby programme on British TV channel ITV1 the claims were "inconceivable".
"These are very serious and important governments. You are not dealing with banana republics," he added.
The allegations were made earlier this month in a report by the US-led Iraqi Survey Group.
Chief US weapons inspector Charles Duelfer said he had found evidence in documents that Iraqi intelligence under Saddam Hussein had tried to bribe foreign nationals from a number of countries to obtain the lifting of sanctions.
Particular attention was allegedly given to French and Russian nationals due to the fact that the two countries hold permanent seats on the UN Security Council.
But Mr Annan firmly dismissed the claims: "I don't think the Russian or the French or the Chinese government would allow itself to be bought because some of their companies are getting contracts from the Iraqi authorities," Mr Annan said.
"I don't believe it at all," he added.
In the same interview, being broadcast on Sunday, the UN secretary general also said the US-led war on Iraq had not made the world a safer place.
"I cannot say the world is safer when you consider the violence around us, when you look around you and you see the terrorist attacks around the world, and you see what is going on in Iraq, " he said.
"We have a lot of work to do as an international community to try and make the world safer."