Tony Blair "must have known" that Shaker Aamer was being illegally tortured at the hands of US authorities in Guantanamo Bay, former SNP leader Alex Salmond has said. In an interview with the BBC, Salmond said Blair and his former Home Secretary Jack Straw need to be asked "straight questions" about whether they knew that British resident was being subjected to torture.

"Governments are not meant to collaborate on the illegal abduction and then the torture of one of our citizens," he told Emily Maitlis this morning. "Both the then-prime minister and home secretary have to face up and tell us exactly what they knew and when they knew it."

Salmond made these extraordinary allegations in response to an interview Shaker Aamer – a UK resident who spent more than 5,000 days in US captivity. Aamer was not charged with any crime. Aamer was finally released by US authorities earlier this year, after spending nearly 14 years in the US military's prison in Cuba.

In his interview, Aamer – a citizen of Saudi Arabia, who was a UK resident in the 1990s – says he was regularly beaten, hog-tied, searched without reason, and kept in protracted periods of solitary confinement. He also claims that in 2002, British intelligence operatives flew to Bagram air base in Afghanistan on the same plane as Tony Blair.

Salmond claims Blair knew

One of these operatives, he alleges, who was a "very white guy with blond hair" and "a posh English accent", was later present during an interrogation at which Aamer repeatedly had his head smashed into a wall.

He told the Mail on Sunday, that: "Then suddenly I feel it – douff – this American guy grabs me by the head, and he slams it backwards against the wall. In my mind I think I must try to save my head so I tried to bring it forwards, but as soon as I do he grabs it again and bashes it: douff, then back again, douff, douff, douff."

Aamer is currently in the process of bringing legal proceedings against the British government over his detention and treatment.

Salmond told the BBC: "The not-unreasonable allegation that Shaker Aamer makes is that both the Prime Minister Tony Blair and the then-Home Secretary Jack Straw must have known not just about his illegal abduction, but also about his torture at the hands of US authorities."