He says his arrest pending an extradition request by a Spanish judge investigating allegations of murder, torture and kidnapping is unlawful.

His lawyers argue that as a former head of state, he was immune from arrest.

The High Court, in London, is expected to make a decision on Wednesday.

Switzerland has also applied for his extradition and Sweden may follow suit.

General Pinochet: Could be tried under UK law

Meanwhile, relations between Chile and Britain deteriorated on Tuesday after the Foreign Office advised British citizens against "non-essential" travel to Chile, saying anti-British feeling is running high following General Pinochet's arrest.

The Foreign Office said: "British nationals and British commercial interests could become targets for spontaneous attacks."

It advised Britons to "keep a low profile, avoid crowds, meetings and demonstrations and avoid areas where English-speaking community usually gather".

The FCO's warning came under fire from the Chilean Deputy Foreign Minister Mariano Fernandez.

He said the warning was "not the best way to avoid the political escalation of this situation".

Such a recommendation from the Foreign Office, he said, was "giving the way for the interpretation that you are facing almost a political conflict. This is not our view."

UK torture charges

It has also emerged that General Pinochet could face torture charges in the UK if the attorney-general consents to a case brought by four alleged victims of his regime.

Lawyers acting for three Chileans living in the UK and a fourth based in Lebanon have requested Attorney-General John Morris's permission to pursue a private criminal prosecution under the Criminal Justice Act 1988.

They have also asked the Director of Public Prosecutions, David Calvert-Smith, to start proceedings against General Pinochet, who was detained in London on 16 October while recuperating after surgery.

The BBC's Joshua Rozenberg: "Torture committed anywhere can be tried in the UK"

He was arrested at the request of Spanish judges. They want to extradite the former dictator to face charges related to more than 4,000 political killings alleged to have taken place during his 1973-1990 rule in Chile.

If the case brought by the four exiles is allowed to proceed, General Pinochet will be arrested under British law, preventing his return to Chile.

British law allows charges of torture and hostage-taking to be tried in the UK, irrespective of where the acts took place.

The lawyer for the four, David Burgess, said: "These are torture victims, not out for revenge, but for justice. They have waited a long time for this."

Fragile democracy

The precise details of the charges have not been made public, but it is known that one of them concerns offences alleged to have been committed against a woman between 1987 and 1989.

On Tuesday, Chilean Socialist Party MP Alejandro Navarro said polls showed more than 50% of Chileans think General Pinochet should face charges.

He denied that Chile's fragile democracy was threatened by the former dictator's arrest.

"In Chile the transition to democracy is very firm. It's not true, as reported, that it is shaking.

"The stability is economic and social as well as political."