Mr Mohamed, a British resident, claims he was tortured in US custody
New guidance for intelligence officers on interviewing overseas detainees will be published in an attempt to show the UK government's opposition to torture.
Gordon Brown said he wanted to restore public faith in the security services and he condemned torture "absolutely".
It follows concerns about the treatment of former Guantanamo Bay detainee Binyman Mohamed.
Mr Mohamed claims he would not have been tortured but for the complicity of UK intelligence officers.
Speaking at prime minister's questions, Mr Brown said he had asked the Intelligence and Security Committee to help draw up new guidelines "in order to have systems that are robust".
He said the guidance would be published to "deal unequivocally with our condemnation of the use of torture".
He told MPs: "I have faith in our security services, we must ensure that the public also have all the faith that is necessary in our security services and we condemn absolutely the use of torture."
Intelligence Services Commissioner Sir Peter Gibson, a former appeal court judge, will monitor compliance with the guidance and report to Mr Brown annually.
The Intelligence and Security Committee, which oversees the work of the intelligence services, will review standards the government believes should apply on the detention and interviewing of overseas detainees.
The Prime Minister's official spokesman earlier said "this would put beyond doubt the terms under which the agencies operate".
On Tuesday, the committee said it had reopened its investigation into rendition, in the wake of new information about the treatment of Mr Mohamed, which it said raised questions about the "policy and procedures" of UK intelligence agencies.
Chairman Kim Howells said the committee had taken fresh "in depth" evidence after MI5 director general Jonathan Evans disclosed last year that the new information had come to light.
The committee - made up of senior MPs and peers - had originally looked into Mr Mohamed's case as part of its inquiry in 2007 into the US policy of "rendition" of terror suspects.
At the time, the committee concluded that MI5 and MI6 had no direct involvement in the rendition programme.
But Mr Mohamed, an Ethiopian national who became a British resident, subsequently claimed through his lawyers that MI5 had been complicit in his interrogation when he was held and tortured at a secret site in Morocco.
Mr Mohamed also claims that he was interviewed for three hours by an MI5 officer while he was being detained in Pakistan. The officer's role, according to Mr Mohamed, was to support the American interrogators.
The MI5 agent who questioned him has previously denied at the British High Court any suggestion that he threatened or put any pressure on Mr Mohamed.
Labour MP Mr Howells said that while the committee did not investigate individual cases, it had been sufficiently concerned about the wider implications of Mr Mohamed's case that it had re-opened its earlier inquiry.
"In this instance we considered that this new evidence had a far wider significance that went beyond an individual case, and that it raised questions about the policy and procedures that our security and intelligence agencies follow," he said.
"As such it was clearly a matter for the Intelligence and Security Committee and we therefore considered that a further detailed investigation was essential.
"As a result we have taken further, in depth, evidence from the intelligence and security agencies, and the Foreign and Commonwealth Office."
The committee had now submitted its findings to Gordon Brown, "including the issues raised about the policies that the UK security and intelligence agencies have followed and should follow".
Mr Mohamed was released from Guantanamo Bay in February having been originally arrested in Pakistan in 2002 travelling on a false passport.
The US authorities alleged that while he was in Afghanistan he underwent terrorist training by al Qaeda - a claim which he denied.
Home Secretary Jacqui Smith has referred his claims against MI5 to the Attorney General, Baroness Scotland.
The US has dropped all charges against Mr Mohamed.