Vice-president Dick Cheney's burden on the Bush administration grew heavier yesterday after a former senior US state department official said he could be guilty of a war crime over the abuse of prisoners.

Lawrence Wilkerson, who served as chief of staff to secretary of state Colin Powell from 2002 to 2005, singled out Mr Cheney in a wide-ranging political assault on the BBC's Today programme.

Mr Wilkerson said that in an internal administration debate over whether to abide by the Geneva conventions in the treatment of detainees, Mr Cheney led the argument "that essentially wanted to do away with all restrictions".

Asked whether the vice-president was guilty of a war crime, Mr Wilkerson replied: "Well, that's an interesting question - it was certainly a domestic crime to advocate terror and I would suspect that it is ... an international crime as well." In the context of other remarks it appeared he was using the word "terror" to apply to the systematic abuse of prisoners.

The Washington Post last month called Mr Cheney the "vice-president for torture" for his demand that the CIA be exempted from a ban on "cruel, inhuman and degrading" treatment of detainees.

Mr Wilkerson, a former army colonel, also said he had seen increasing evidence that the White House had manipulated pre-war intelligence on Iraq to make its case for the invasion. He said: "You begin to wonder was this intelligence spun? Was it politicised? Was it cherry-picked? Did, in fact, the American people get fooled? I am beginning to have my concerns."

Mr Cheney has been under fire for his role in assembling evidence of weapons of mass destruction. Mr Wilkerson told the Associated Press that the vice-president must have sincerely believed Iraq could be a spawning ground for terrorism because "otherwise I have to declare him a moron, an idiot or a nefarious bastard".

Such charges have kept the Bush administration on the defensive for several months. Mr Bush yesterday repeated his earlier assertion that the US "does not torture and that's important for people around the world to realise". He is also due to make the first of a series of speeches today, outlining his plan to defeat the insurgency and pave the way for US withdrawal. The White House will also publish a declassified version of its war plan.

But it has now emerged that two justice department memos listing permissible interrogation methods have been kept secret by the White House, even from the Senate intelligence committee. The New Yorker recently quoted a source who had seen a memo as calling it "breathtaking".

"The document dismissed virtually all national and international laws regulating the treatment of prisoners, including war crimes and assault statutes, and it was radical in its view that in wartime the president can fight enemies by whatever means he sees fit," the magazine reported.

One technique allegedly used by the CIA in questioning suspects is "waterboarding" (strapping a detainee to a board and submerging it until the prisoner believes he or she is drowning). The White House is accused of defining "torture" so narrowly as to exclude such methods. But James Ross, a legal expert at Human Rights Watch said such a narrow definition was at odds with international norms.

"Waterboarding is clearly a form of torture. It has been used since the Inquisition. It was a well-known torture technique in Latin America," Mr Ross said.

Human Rights Watch this year called for a special counsel to investigate any US officials - no matter their rank or position - who took part in, "ordered, or had command responsibility for war crimes or torture, or other prohibited ill-treatment against detainees in US custody".

The report focused on the defence secretary, Donald Rumsfeld, for his alleged command responsibility for abuses at Abu Ghraib, but Mr Wilkerson argued Mr Cheney was ultimately responsible.

The US is a signatory to the 1984 UN Convention Against Torture, which bans inflicting "severe pain or suffering, whether physical or mental". Such practices are also a crime under US federal law.