Home Secretary Jack Straw: A decision will be based on the facts of the case

Mr Straw said the extradition request would go through the normal legal channels and be treated impartially, despite the enormity of the crimes alleged against the 82-year-old.

The general, who seized power in Chile in 1973, was arrested on Friday night at a private London hospital. He faces the prospect of questioning about the mass murder of Spanish citizens during his military dictatorship.

"So far as my position is concerned, I will treat this extradition request by Spain in the same way as I treat any other extradition request," Mr Straw said.

Jack Straw: Protested as a student against Pinochet

The home secretary stressed that this was a legal process and that political factors did not come in to play.

"I will act on this as on any other matter, in a quasi-judicial way. I will act on the facts of the case," Mr Straw said.

Chile has officially protested against General Pinochet's arrest and the country's government has dispatched the prominent diplomat, Santiago Benadava, to London, in the hope that he can persuade the UK to release him.

Diplomatic immunity

Speaking on Radio 4's Today programme, Mr Straw dismissed the suggestion that the Metropolitan Police's arrest of Pinochet violated diplomatic immunity rules.

He argued that it was doing a diplomat's job, rather than having the diplomat's passport, that conferred diplomatic immunity.

"Someone may have a diplomatic passport without being accredited as a diplomat to a country."

Downing Street confirmed that there had been no political input into the extradition decision.

Pinochet confident

General Pinochet later issued a statement through London solicitors, saying he was confident of successfully opposing extradition.

The statement said that the general had entered the UK with the full knowledge of the government and with the Foreign Office's approval.

"Permission for him to enter and stay in this country was stamped in his diplomatic passport.

"Over recent years General Pinochet has travelled without hindrance to the UK on several occasions with the approval of Her Majesty's Government.

"Any attempt to extradite him from the UK will be resolutely opposed. Both he and his family are confident of success."

Opinion within the government in recent days appears to be pressing for Mr Straw, known in his student days as a vehement opponent of the Pinochet regime, to take a strong line on extradition.

Angry scenes in Chile during protests at Pinochet's arrest

Labour MP Ann Clywd, chairman of the all-party human rights group, has tabled a motion in the House of Commons on Monday calling for "close co-operation" with the Spanish authorities.

Trade and Industry Secretary Peter Mandelson has already condemned General Pinochet as a "brutal dictator".

But the general's arrest has attracted concern among UK opposition politicians.

Former Defence Minister, Alan Clark MP called General Pinochet's detention "monstrous".

"It shows that if something is politically correct or they deem it to be, the government will simply fall over themselves to appease any particular lobby regardless of the legal correctness," he told Radio 4's World at One.

Speaking on the same programme, former Home Secretary Kenneth Clarke MP said that he was worried about the UK's relations with Chile in light of the general's arrest.

Referring to Mr Mandelson's comments, he added: "It is not helpful ... for another member of the Cabinet to be going around and making some of the speeches, I suspect, that Mandelson used to make in his more left-wing days."

The extradition process will begin with hearings at Bow Street magistrates court in London.

If the decision goes against him, the general would have a right of appeal to the Lords judicial committee, and the issue could then be referred to the Home Secretary for a final decision.