By James Reynolds in Santiago

Some 643 former political prisoners in Chile have filed a lawsuit against General Augusto Pinochet, accusing the former military leader of torture.

This is the 59th lawsuit submitted in Chile against General Pinochet.

The general is currently under house arrest in London. Earlier this month, the British Home Secretary, Jack Straw, said that he was minded to return him to Chile on health grounds.

'Degrading crimes'

The text of the lawsuit accuses the former military leader of responsibility for cruel, inhuman and degrading crimes, which it argues cannot be covered by any amnesty laws.

After filing the lawsuit at the headquarters of Chile's judiciary, several hundred former prisoners held a demonstration against General Pinochet's possible return to Chile on health grounds.

Many say that although they would like the former military leader to face trial here, they do not believe that justice will be done in Chile.

It is expected that this lawsuit will be added to the 58 others currently being handled by Chilean judge Juan Guzman.

For the last two years, Mr Guzman has been investigating whether there is sufficient evidence to warrant a trial of General Pinochet in Chile.

The judge says that he will decide within two months whether he has found enough evidence to proceed with the trial.

Trial 'unlikely'

Mr Guzman also says that if General Pinochet returns to Chile soon, he will order new medical tests to be carried out on the general to determine whether he is mentally fit to stand trial.

But many observers say that a trial here is still unlikely. The 1978 amnesty law is still in force, and at present, Augusto Pinochet has parliamentary immunity as a life senator.

He can also choose to have any case against him heard by a military tribunal, not a civilian court.