Mr Mohamed arrived back at RAF Northolt in London in February
MPs have demanded a judicial inquiry into a Guantanamo Bay prisoner's claims that MI5 was complicit in his torture.
In a Mail on Sunday interview, UK resident Binyam Mohamed claims MI5 fed his US captors questions, at a time he said he was being tortured in Morocco.
His allegations are being investigated by the government, but the Foreign Office said it did not condone torture.
Shadow justice secretary Dominic Grieve said the "extremely serious" claims should also be referred to the police.
Mr Mohamed told the paper he was held in continual darkness for weeks on end in a prison in Kabul, Afghanistan.
He has claimed that while in US custody in 2002, he was rendered to Morocco for interrogation and torture, which led to him making a false confession.
Now he has released what he said were two telegrams sent from British intelligence to the CIA in November 2002.
In the first memo, the writer asks for a name to be put to him and then for him to be questioned further about that person.
The second telegram asks about a timescale for further interrogation.
The legal organisation Reprieve, which represents Mr Mohamed, said its client was shown the telegrams in Guantanamo Bay by his military lawyer Lieutenant Col Yvonne Bradley.
Mr Mohamed claimed he acquired the telegrams through the US legal process when he was fighting to be freed from Guantanamo Bay.
Daniel Sandford, BBC Home Affairs correspondent, said Mr Mohamed's claims would be relatively simple to substantiate.
"As time progresses it will probably become quite apparent whether indeed these are true telegrams and I think it's unlikely they'd be put into the public domain if they couldn't eventually be checked back."
The Conservatives have called for a police inquiry into his allegations of British collusion.
Mr Grieve called for a judicial inquiry into the allegations.
"And if the evidence is sufficient to bring a prosecution then the police ought to investigate it," he added.
Liberal Democrat foreign affairs spokesman Ed Davey said there was a "rock solid" case for an independent judicial inquiry.
Labour MP Andrew Dismore, who chairs the joint committee on human rights, said he would be asking the home and foreign secretaries to explain how Britain's policy against torture is being implemented and monitored.
Shami Chakrabati, director of campaign group Liberty said: "These are more than allegations - these are pieces of a puzzle that are being put together.
"It makes an immediate criminal investigation absolutely inescapable."
Former Conservative shadow home secretary David Davis accused the government of "stonewalling" by referring the claims to the Attorney General rather than the Director of Public Prosecutions.
"What appears to have happened is they have been turning blind eyes," he added.
Mr Mohamed told the paper the worst part of this captivity was in Kabul's "dark prison".
"The toilet in the cell was a bucket," he told the paper.
"There were loudspeakers in the cell, pumping out what felt like about 160 watts, a deafening volume, non-stop, 24 hours a day.
He added: "They chained me for eight days on end, in a position that meant I couldn't stand straight nor sit.
"I couldn't sleep. I had no idea whether it was day or night."
Mr Mohamed spent just under seven years in custody, four of those in Guantanamo - the US's camp in Cuba.
He was arrested in Pakistan in 2002 as US authorities considered him a would-be bomber who fought alongside the Taleban in Afghanistan.
But last year the US dropped all charges against him, and he was released in February.
A Foreign Office spokesman said: "We abhor torture and never order it or condone it.
"We take allegations of mistreatment seriously and investigate them when they are made.
"In the case of Binyam Mohamed, an allegation of possible criminal wrong-doing has been referred to the Attorney General.
"We need now to wait for her report."