Binyam Mohamed, a former UK resident who is flying home after four years of incarceration at Guantánamo Bay, today accused Britain of involvement in his alleged torture.

"I have to say, more in sadness than in anger, that many have been complicit in my own horrors over the past seven years," he said in a statement his lawyers released shortly before the chartered plane bringing him back from the US detention camp in Cuba was due to land at RAF Northolt, near London.

"For myself, the very worst moment came when I realised in Morocco that the people who were torturing me were receiving questions and materials from British intelligence," he said.

"I have met with British intelligence in Pakistan. I had been open with them. Yet the very people who I had hoped would come to my rescue I later realised had allied themselves with my abusers.

"I am not asking for vengeance, only that the truth should be made known so that nobody in the future should have to endure what I have endured."

The Ethiopian-born 30-year-old has previously accused the UK of having knowledge of what he says was widespread torture during his time in detention, and of being involved in the interrogation process by providing and receiving information.

The Metropolitan police said officers from its anti-terrorism unit were on board the plane with Mohamed, as well as uniformed police acting as an escort.

Mohamed's plane is expected to land at around 1pm. He will be met by a doctor and his UK lawyers, Clive Stafford Smith and Gareth Peirce, along with family members.

Mohamed was arrested in Pakistan in 2002 and then secretly flown by the CIA to Morocco where he says he was brutally tortured. He was subsequently flown to Afghanistan and then to the US camp in Cuba.

In his statement today, Mohamed said he would not be able to speak publicly about his experiences for some time.

"I hope you will understand that after everything I have been through I am neither physically nor mentally capable of facing the media on the moment of my arrival back to Britain," he said. "I have been through an experience that I never thought to encounter in my darkest nightmares.

"Before this ordeal, torture was an abstract word to me. I could never have imagined that I would be its victim. It is still difficult for me to believe that I was abducted, hauled from one country to the next, and tortured in medieval ways - all orchestrated by the United States government.

"While I want to recover, and put it all as far in the past as I can, I also know I have an obligation to the people who still remain in those torture chambers.

"My own despair was greatest when I thought that everyone had abandoned me. I have a duty to make sure that nobody else is forgotten."

Mohamed ended a month-long hunger strike 10 days ago after visits from his lawyers, Foreign Office officials and a UK doctor, who passed him fit to travel. He has agreed to abide by several voluntary security measures in Britain including regular reports to a police station, the Guardian has learned.

His lawyers readily agreed to the undertakings as Mohamed "has nothing to hide", said Stafford Smith, director of Reprieve, the human rights group that represents him. Mohamed and his lawyers rejected a gagging order the US tried to impose on him, the Guardian understands.

Stafford Smith, said he was "absolutely" convinced of Mohamed's innocence. "If anyone wants to put him on trial, in the immortal words of George Bush, bring them on," he said.

Mohamed's return to the UK after seven years in custody comes as pressure is building on the British and US governments to disclose evidence of his alleged torture and what the UK agencies MI5 and MI6 allegedly knew about it.

There is a growing belief that documentary evidence exists pointing to Downing Street's awareness of allegations of the serious mistreatment of Mohamed between 2002 when he was first seized in Pakistan and 2004 when he was abducted and flown to Guantánamo Bay.

US documents that high court judges say contain "powerful evidence" relating to Mohamed's allegations are being suppressed because, the judges said this month, David Miliband, the foreign secretary, argued that their disclosure would damage Britain's national security. It would do so, he argued, because the US had warned it might cut off intelligence co-operation if the papers were released.

The documents may show how British officials allegedly co-operated with the CIA even though they did not know where Mohamed was being held and in what conditions. The CIA refused to tell MI5 of his whereabouts – it is now known he was being held in Morocco – after an MI5 officer questioned him when he was being detained incognito in Pakistan.

Lord Carlile QC, the government's independent reviewer of terror laws, yesterday called on Miliband to release details from the documents about Mohamed's treatment. Carlile told the Sunday Telegraph: "If wrong has been done by any British official it would be better to say so now than after a lengthy period of attrition. If there is a sore here it should be lanced as soon as possible. This has gone on for a long time."