The government yesterday bowed to growing pressure over allegations of Britain's complicity in torture by promising to draw up and publish new guidelines for the security and intelligence agencies when they are involved in interrogating detainees abroad.

Announcing the unexpected move to MPs, Gordon Brown said he condemned torture "absolutely" but had asked the intelligence and security committee (ISC) to help draw up new guidelines "in order to have systems that are robust".

In a separate move, the prime minister told MPs that compliance with the new guidelines would be monitored by intelligence services commissioner Sir Peter Gibson, a former appeal court judge, who will report annually.

Brown's announcement, which follows a succession of revelations in the Guardian about the ill-treatment and torture of UK nationals and residents abroad, appeared to be a tacit admission that existing guidelines were open to abuse. It was also seen as an attempt to resist calls for an independent inquiry into growing evidence of British complicity in the interrogation of suspects held in Pakistan and Morocco.

But it did not satisfy campaigners and parliamentary critics who want a full independent inquiry into torture, rendition and alleged British collusion.

Andrew Tyrie MP, chairman of the all- party parliamentary group on extraordinary rendition, said: "The prime minister's announcement is inadequate ... Lord Carlile, the government's own independent reviewer of terrorism legislation, has concluded that a judge-led inquiry is necessary. I agree."

Amnesty's UK campaigns director, Tim Hancock, said: "If the prime minister thinks this will silence calls for a full, impartial inquiry into UK collusion in torture and rendition, he should think again".

Brown's statement came after the ISC took the unprecedented step of reopening its investigation into the treatment of Binyam Mohamed, the British resident recently released from Guantánamo Bay. Kim Howells, former Foreign Office minister and new chairman of the ISC, said it had taken the decision because of new information on the case provided by Jonathan Evans, the head of MI5.

The committee, which has oversight of the security services, has been criticised for not being sufficiently independent. It meets in private and sends reports to No 10 for vetting before publication.

Howells said yesterday that its role was to examine the expenditure, administration and policy of the security and intelligence agencies. He added: "However, 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 they had made recommendations to the prime minister. Although Howells did not say what they were, it seems clear that they related to the lack of rigour in existing guidelines.

Well-placed Whitehall officials said last night that in the aftermath of the 9/11 attacks on the US, "proper procedures" were not kept. They also said Britain's security and intelligence agencies had to co-operate with foreign agencies which had lower standards.

Brown 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."

He said earlier in a prepared written statement: "They take significant personal risks to make Britain more secure and operate across the world in circumstances they do not control."

Reprieve, the legal charity that represents Mohamed, welcomed the statement. But Clare Algar, its executive director, said Brown was "trusting people who were deeply involved in the security services to check their conduct. It is ludicrous to suggest that this will restore public confidence."