The Tories are calling on Home Secretary Jack Straw to deliver a statement to the House of Commons on Monday.

The move came as lawyers prepared to renew their efforts to free the former Chilean ruler General Augusto Pinochet who is being detained in London and facing possible extradition to Spain for the murders of Spanish nationals during his rule.

BBC correspondent Jane Bennet Powell: The former dictator's arrest continues to put the British government under pressure

The ailing general is being held in a private clinic where he is recovering from back surgery. Chile argues that he has diplomatic immunity and should be released.

It emerged on Sunday that the former military ruler was given a VIP welcome by the UK Foreign Office when he arrived in Britain. A suite at Heathrow Airport was reserved and paid for by the Foreign Office at the request of the Chilean ambassador.

Robin Cook discusses the Pinochet case with David Frost

Foreign Secretary Robin Cook, speaking on BBC's Breakfast With Frost, confirmed that the UK Government had been informed in advance of General Pinochet's visit and said the "standard, routine procedures" for a visit by an ex-head of state had been made.

Chile expects the general to disappear from political life

He also confirmed General Pinochet had visited London in similar circumstances in the autumn of 1997.

But Shadow Home Secretary Michael Howard accuses Jack Straw of misleading the House of Commons over the Pinochet case.

He says Mr Straw told MPs last week that General Pinochet's visit was the first he had made to London since last year's General Election.

Shadow Home Secretary Michael Howard: "The government has made a mess"

"I think Jack Straw should come to Parliament tomorrow (Monday) to clear up the mess that surrounds this whole issue. The more one learns about it, the murkier it gets," he said.

On Saturday Mr Cook turned down a formal request from Chile to release the Gen Pinochet.

Mr Cook told Chilean Deputy Foreign Minister Mariano Fernandez it was neither "proper nor possible" for the UK Government to intervene in the extradition proceedings.

'Case should not harm UK-Chile relations'

But at a meeting at the Foreign Office, Mr Cook told Mr Fernandez he did not want the extradition case to "spill over" and damage Britain's relations with Chile.

Robin Cook: "We cannot interfere in the legal process"

Mr Cook denied suggestions in some Sunday newspapers that Gen Pinochet had been lured to London so he could be extradited to Spain.

He told David Frost: "There was no contact between the Foreign Office and the Spanish government prior to Mr Pinochet's arrival. There was no entrapment in this case."

He said London's Metropolitan Police had approached the Foreign Office's protocol department for guidance when they received the extradition warrant from Madrid. They were told that Gen Pinochet did not have diplomatic immunity.

Mr Cook said it was vital in a democracy for politicians to stay out of the legal process and added: "We can't chip away at that principle without setting precedents which will come back to haunt us."

He said if the Foreign Office had stopped the police from arresting Gen Pinochet the UK would be "one step away" from a system in which the government told the police who to arrest.

Support for diplomatic immunity claim

The Chilean Foreign Ministry said a formal note was handed to British ambassador Glynne Evans on Friday with new legal information to support Chile's claim that the general has diplomatic immunity.

Foreign Minister Jose Miguel Insulza said the Chilean Government expected the ailing former dictator to "disappear from our political life" once he got back home.

Braving the British weather to protest outside the clinic

He added: "When General Pinochet comes back to Chile, he should go to his house. That is the government's position. This country can no longer be subject to the tensions and divisions that his figure causes."

On Saturday more than 150 protesters stood in driving wind and rain outside the clinic where General Pinochet is recovering from back surgery calling for him to be brought to justice.