Judge Roger Leloire is investigating the disappearance of Frenchmen Marcel Amiel-Baquet, Rene Chanfreau and Etienne Pesle during General Pinochet's rule in the early 1970s.

The French warrant was issued as the UK's Crown Prosecution Service appealed against last week's ruling by the High Court in London that General Pinochet was immune from prosecution because he is a former head of state - a protection known as "sovereign immunity".

The appeal was lodged on behalf of the Spanish authorities, who have sought the general's extradition.

Spanish judge Baltasar Garzon wants the general to answer charges of genocide and torture allegedly committed against Spanish nationals in Chile during his 18-year rule.

Legal Affairs Correspondent Joshua Rozenberg: "If he's got immunity, he's got immunity whichever country is involved"

The appeal now transfers to the highest UK court, the Law Lords, who will rule this week on whether General Pinochet should remain in custody.

Following the High Court ruling the general was released on bail pending the appeal to the Law Lords.

However, the 82-year-old must remain under police guard in the north London clinic where he was arrested two weeks ago.

General Pinochet: Remains under guard

The BBC's Legal Affairs Correspondent Joshua Rozenberg says the French authorities may not be able to make a formal extradition request for some time.

By then the law lords may already have made their decision and if they confirm that the general has immunity, it will make no difference whichever country is involved.

Earlier the French Justice Minister, Elisabeth Guigou, told the French Senate: "The idea of immunity for someone like General Pinochet, who is responsible for several thousand murders, is unbearable."

Isabel Allende: Pinochet must be prosecuted

On Monday a delegation of leading opponents of General Pinochet arrived in London from Chile to support the appeal against the High Court's decision.

"We are fighting for justice," said Isabel Allende, daughter of the late Salvador Allende, the socialist president toppled by General Pinochet in a 1973 coup.

Isabel Allende: "It is necessary to have justice"

The Chilean Government has appealed to Britain to release the general on humanitarian grounds, saying his arrest threatens to split the country's new democracy, built after he stepped down in 1990.

However, that argument was rejected by Ms Allende. She said it would be the "worst" outcome for democracy if the former dictator was not held to account for his crimes.