The most damning fresh testimony came from Tariq Aziz, the former Deputy Prime Minister, who told the Senate Permanent Subcommittee on Investigations that Iraq granted Mr Galloway oil allocations to help to fund his Mariam Appeal. The investigators said Mr Aziz also told them that a letter allegedly recording a request by Mr Galloway for an increased “share of oil” is authentic. The letter, found in a government building, purports to be from the Iraqi Intelligence Service, dated January 2000.

Mr Galloway’s challenge to the letter’s authenticity was at the heart of a successful libel action he took against Telegraph Newspapers. The case is under appeal. Mr Galloway said his accusers from Saddam’s regime were all under sentence of death and Mr Aziz had been offered a deal to testify.

Taha Yasin Ramadan, the former Vice-President of Iraq, told the subcommittee that Mr Galloway had been granted oil allocations “because of his opinions about Iraq” and because he “wanted to lift the embargo against Iraq”. He added that Mr Galloway was “a friend of Iraq” and “needed to be compensated for his support”.

Mr Ramadan said: “Galloway needed money to pay for his actions” and “We gave him oil to sell to make the money.”

Mr Aziz said: “The oil allocations we gave to George Galloway were in the name of either (Burhan al-) Chalabi or to (Fawaz) Zureikat.” He also said: “The oil was allocated in the name of Zureikat and Chalabi, once or twice. These oil allocations were for the benefit of George Galloway and for Mariam’s Appeal. The proceeds from the sale benefited the cause and Mr Galloway.”

Asked if Mr Galloway had been granted oil allocations, Amer Rashid, the former Oil Minister, replied: “Yes.” He described Zureikat as “the oil lifter” for Mr Galloway.

Mr Galloway said last night: “I’ve never met Ramadan or Rashid but they are facing charges which may carry a death sentence, as is Tariq Aziz. He has been held incommunicado for two years and we know that he has been offered a deal to testify.

“On the one hand the US Government accuses these men of being homicidal maniacs, on the other they assert that their coerced testimony is utterly trustworthy. Let Senator Coleman bring them and his unnamed sources to court in a case against me, and we’ll see what the world concludes.”

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