Gordon Brown yesterday strongly defended MI5 after the Security Service was strongly criticised by a senior judge over its role in the case of former Guantanamo Bay detainee Binyam Mohamed.

The Prime Minister said in a statement that he had spoken to MI5 director general Jonathan Evans to express his gratitude for the work the service did protecting the public.

He also announced that the government would "shortly" be publishing its revised guidelines for the intelligence agencies on the treatment of detainees held overseas.

"The United Kingdom has the finest intelligence services in the world. I have seen for myself their immense bravery and expertise in our defence," Mr Brown said.

"It is the nature of the work of the intelligence services that they cannot defend themselves against many of the allegations that have been made. But I can - and I have every confidence that their work does not undermine the principles and values that are the best guarantee of our future security.

"We condemn torture without reservation. We do not torture, and we do not ask others to do so on our behalf. We are clear that officials must not be complicit in mistreatment of detainees.

"Wherever serious allegations of potential criminal wrongdoing are made, they are referred to the appropriate authorities."

Mr Brown originally announced last March that he would release the guidance given to intelligence officers and the military on the interrogation of detainees held overseas once it had been reviewed by the parliamentary Intelligence and Security Committee.

Meanwhile Foreign Secretary David Miliband dismissed suggestions that MI5 had lied over its involvement in Mr Mohamed's case.

"I completely reject any suggestion of lies," he said.

"The judges have a complete right to express their opinions, that is important in a free society. Equally, the government doesn't have to agree with everything they say."