British MP George Galloway has told US senators who accused him of profiting from Iraq oil dealings their claims were the "mother of all smokescreens".
In a combative performance before a Senate committee, the Respect Coalition MP accused the US lawmakers of being "cavalier" with justice.
He said: "I am not now nor have I ever been an oil trader and neither has anyone on my behalf."
The senators say he was given credits to buy Iraqi oil by Saddam Hussein.
Mr Galloway travelled to Washington to clear his name before the Senate sub-committee on investigations.
He claims the evidence against him is false. He says forged documents had been used to make claims about him before.
Mr Galloway went on the offensive from the start of his testimony, saying the committee had "traduced" his name around the world without asking him a single question.
He told committee chairman Senator Norm Coleman: "I know that standards have slipped over the last few years in Washington but for a lawyer you are remarkably cavalier with any idea of justice."
Mr Galloway said he had met Saddam Hussein on two occasions - the same number of times as US Defence Secretary Donald Rumsfeld.
"The difference is Donald Rumsfeld met him to sell him guns and maps - the better to target those guns. I met him to try to bring about an end to sanctions, suffering and war," he said.
The biggest sanctions busters were American companies "with the connivance" of the US Government, he argued.
And he denied being an "apologist" for Saddam.
He said he had been a long-term opponent of the former Iraqi leader, and had a much better record of opposition to his regime than members of the American or British governments.
Mr Galloway, a leading anti-war campaigner, was expelled from the Labour Party for his comments on Iraq.
He is not accused of any criminal act and is not thought likely to face court action as a result of the committee's hearings but he has said he is anxious to clear his name.
At this month's UK general election, Mr Galloway narrowly beat Labour's Oona King to win the Bethnal Green and Bow constituency, in East London, for his fledgling Respect party.
The United Nations-backed oil-for-food scheme enabled Saddam Hussein to export oil to pay for essential humanitarian aid to help the Iraqi people cope with UN sanctions imposed in 1991.
Options to buy barrels of Iraqi oil were alleged to have been given as rewards for supporting Saddam Hussein.
The former Iraqi leader sold the vouchers at below market prices to favoured parties, who were able to sell them on at profit.
One of the main allegations raised by the Senate sub-committee is that Mr Galloway received oil allocations with the assistance of Fawaz Zureikat.
Mr Zureikat, who was chairman of the Marian Appeal set up by Mr Galloway to help a four year old Iraqi girl with leukaemia, has strongly denied making any arrangements linked to oil sales on behalf of the MP.
Mr Galloway told the senators: "I can assure you Mr Zureikat never gave me a penny from an oil deal, a cake deal, a bread deal or from any other deal.
"He donated money to our campaign, which we publicly brandished on all our literature along with all the other donors to the campaign."
On Monday Russian politician Vladimir Zhirinovsky denied the committee's accusations that he accepted millions of dollars in Iraqi oil allocations.
In December, Mr Galloway won £150,000 in libel damages from the Daily Telegraph over its separate claims he had received money from Saddam's regime.
Last month the newspaper won permission to appeal against the ruling to pay the damages, plus £1.2m in costs.
The Senate committee's report also accused former French minister Charles Pasqua of receiving oil rights from Iraq, something he has vehemently denied.