Lawyers for Gen Pinochet, who is staying in a rented mansion in Wentworth, Surrey, are expected to lodge a request for a judicial review by the High Court.

But his solicitors, Kingsley Napley, have refused to confirm they will apply on Thursday for leave to seek a High Court judicial review.

The 83-year-old could now be sent to Spain for trial on charges of mass murder.

Joshua Rozenberg reports on "the last thing the Chilean government wanted"

He will appear at Belmarsh Magistrates Court in south-east London on Friday.

In a 30-paragraph statement, Mr Straw rejected all the grounds put forward by supporters of the former dictator, who wanted him to be sent back to Chile immediately.

The BBC's Paul Reynolds reports on reaction in Chile

Mr Straw said Gen Pinochet did not enjoy immunity from prosecution and was fit to face extradition proceedings. He also rejected claims that the involvement of one of the Law Lords with Amnesty International could have influenced the earlier ruling.

He said the length of time which had elapsed since the alleged crimes was also irrelevant.

Mr Straw's announcement follows a ruling in the UK's highest court, the House of Lords, that Gen Pinochet did not have immunity from prosecution.

Chile reacted to the decision by announcing the withdrawal of its ambassador in London, Mario Artaza.

The ambassador said: "I have to believe that this is a quasi judicial decision. There were other factors involved - it was more than just a judicial judgement."

A Chilean embassy spokeswoman said: "It is to give more information and is also a gesture."

In the Chilean capital, Santiago, British Embassy staff are battening down the hatches in preparation for angry demonstrations.

Amnesty International, which has been campaigning for Gen Pinochet to face a trial, hailed the decision as the start of a "new era for human rights" and said Mr Straw should be congratulated for "not bowing to political pressure".

Luis Machivello, of the Families of the Disappeared, said: "It is such a good day for human rights.

"A lot of atrocities were committed and now he needs to pay."

Michael Zander, professor of law at the London School of Economics, says it is a global landmark decision

But former prime minister Baroness Thatcher said the decision was a "grave mistake".

She said: "Jack Straw had ample to power to put an end to this shameful and damaging episode."

Lady Thatcher said the decision represented a "failure of political leadership".

Jack Straw: "I have decided to issue an authority to proceed"

If Gen Pinochet's lawyers, Kingsley Napley, are granted leave for a judicial review they are expected to raise a number of matters.

One of these is the alleged bias of Lord Hoffmann, the Law Lord whose vote won the day for supporters of the extradition process. He is a director of a charity linked to Amnesty International.

John Andrew outside the High Court: "Mr Straw stresses he is not acting as a politician"

Chilean MP Dario Paya says Lord Hoffmann's role in the saga meant the Law Lords' decision was "tainted" but Amnesty lawyer Geoffrey Bindman says he is a conscientious and independent-minded judge.