He defended the UK's decision to arrest Gen Pinochet in London last Friday after receiving an extradition request from a Spanish court.

He told BBC Radio 4's Any Questions: "I think it is absolutely right that we should insist that the courts take their course with this application of extradition."

Baroness Thatcher: Letter to The Times sparked controversy

Referring to Baroness Thatcher's letter to The Times calling for his release, he said: "Traditionally the Conservatives have often supported the rule of law.

"Frankly I find it rather surprising in the last few days that many of them have questioned whether the rule of law should be paramount when it is one of their pals who comes up against it."

Baroness Thatcher had argued that Gen Pinochet saved British lives in the Falklands War and should therefore be released as an ally.

She said: "General Pinochet must be allowed to return to his own country forthwith."

Several Conservatives have agreed with her, including David Wilshire MP, a member of the Commons foreign affairs select committee.

He backed her intervention as "absolutely right".

Cook denies plot

Mr Cook has also denied that British and Spanish authorities plotted Gen Pinochet's arrest in advance of his arrival in London on 22 September.

In a written response to the Shadow Foreign Secretary, Michael Howard, Mr Cook said: "Neither the government nor the police had any contact with the Spanish authorities regarding the visit before Senator Pinochet arrived in this country."

General Pinochet is appealing against his detention

Mr Howard had asked whether there had been any liaison between British and Spanish authorities before the visit.

Mr Cook added: "This was a matter for the police. At no stage did FO officials warn the Spanish authorities of any plans for Senator Pinochet to leave the UK."

Mr Cook, taking part in a 50th birthday edition of Any Questions, also welcomed the forthcoming visit of Argentine President Carlos Menem, who is expected to step into row surrounding Gen Pinochet.

Mr Cook said: "It is surely right now that we should start to forge a new relationship with what is a democracy in the south Atlantic with whom we share many interests."

President Menem has supported Chilean Government demands that Gen Pinochet be released.

Earlier, officers from the extradition unit of Scotland Yard's organised crime group served a new warrant on 82-year-old at the west London clinic where he is being held and recuperating from back surgery.