The case was referred to police by the Attorney General, Baroness Scotland, earlier this year.
A Met spokesman said: “The Metropolitan Police Service (MPS) was invited by the Attorney General to investigate allegations surrounding the detention of Binyam Mohamed.
“The papers were reviewed by the MPS and the investigation accepted. A team of detectives, working to Deputy Assistant Commissioner Sue Akers, has now been selected and vetted to appropriate levels. As a result a criminal investigation has now begun.
“The inquiry team is in close liaison with the Crown Prosecution Service and will regularly consult them as the investigation moves forward.
“Inquiries will be conducted as expeditiously but thoroughly as possible and will follow the evidence to identify whether any offences have occurred.”
Mohamed, 30, a former UK resident, was arrested in Pakistan in 2002. He alleges that, during three months of detention, he was tortured by Pakistani agents and interrogated by the FBI and MI5.
He says he was then taken to Morocco after being subject to “extraordinary rendition” by the CIA with the explicit knowledge of the Security Service.
During further torture in Morocco, he says he became aware that his torturers were being fed questions and material from British intelligence agents. Ethiopian-born Mohamed, who lived in London before his arrest, was then taken to Guantanamo Bay, where he stayed for four years before returning to this country on February 23.
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