A Spanish judge who won fame with his attempt to extradite former Chilean dictator Augusto Pinochet in the 1990s denied breaching the rights of defendants on Tuesday in a trial many supporters say is a politically motivated vendetta against him.

Baltasar Garzon, who wore his robe of office for his appearance, faces three cases in his home country linked to his investigations into human rights abuses, corruption and other offences.

Garzon was once admired across the political spectrum in Spain for heading investigations against the Basque separatist group ETA.

He is also uncovered the death squads run by the Socialist government in the 1980s in its conflict with ETA, a probe credited with helping the centre-right defeat the left in 1996 elections.

But he alienated many Spaniards with his attempt to order an investigation into the killing of tens of thousands of civilians during the four-decade dictatorship of General Francisco Franco, who died in 1975.

The first case, which opened on Tuesday, against the suspended High Court judge involves allegations he illegally authorised police investigating a corruption case to record the conversations of lawyers with their clients in custody.

He violated the rights he said he defended, Ignacio Pelaez, a lawyer for the prosecution case, told Reuters outside the court.

I want the Supreme Court to put limits on judges ... to respect the right to a defence ... to say not everything goes in a prosecution.

Garzon told the court he had authorised the taping of conversations of defendants in custody only because lawyers were suspected of involvement in money laundering.

Tuesday's case was brought by two businessmen who are awaiting trial for allegedly bribing members of the centre-right People's Party (PP), which won a landslide election victory in November.

The conversations were taped...for a concrete and specific reason, that had nothing to do with their defence preparation, Garzon told Spain's Supreme Court.

All and every measure was taken to protect the right to a (fair) defence.

LANDMARK PINOCHET MOVE

Garzon's attempt to extradite Pinochet from Britain in 1998 to face charges of human rights abuses following the dictator's 1973 coup in Chile set a precedent for the principle that crimes against humanity can be investigated anywhere.

Over the years, Garzon has investigated cases involving prisoners at Guantanamo Bay and victims who disappeared during the 1970s dictatorship in Argentina.

Tuesday's case and two other pending trials against Garzon are private prosecutions, brought by individuals and organisations rather than the state, against the recommendation of Spain's public prosecutor who has recommended Garzon's acquittal on all the charges.

The judge will face a separate trial over allegations he overstepped his powers by trying to apply the principle of universal justice despite a 1977 Spanish amnesty law which paved the way for Spain's transition to democracy.

In the third case, Garzon faces allegations he dropped an investigation into the head of Spain's biggest bank, Santander, after receiving payments for a course sponsored by the bank in New York.

If Garzon were convicted in any of the cases, he could be barred from office for up to 20 years - a career-ending blow for the 56-year-old judge.

Supporters of Garzon turned out in front of Spain's Supreme Court to greet the judge on his arrival, with placards proclaiming his innocence.

Among the supporters were victims of Spain's right-wing dictatorship, which lasted until the late 1970s, and a representative of an Argentine human rights group, who see Garzon as a hero.

What bitter irony that Garzon is being prosecuted for trying to apply at home the same principles he so successfully promoted internationally, said Reed Brody, counsellor and spokesman for Human Rights Watch.

Absent clear and compelling circumstances, prosecuting a judge for his judicial acts undermines judicial independence.

A number of international lawyers, human rights organisations and left-wing artists, including Spanish film director Pedro Almodovar, have come out in support of Garzon.

Among supporters who greeted Garzon at the court was celebrated actress Pilar Bardem, mother of the international screen star Javier.

(Additional reporting by Sarah Morris, Marco Trujillo, Juan Medina and Andrea Comas; Writing by Sarah Morris; Editing by Fiona Ortiz and Jon Boyle)