LONDON, Jan 25: Human rights group and authorities in Belgium were preparing legal challenges today to thwart moves to release former Chilean dictator Augusto Pinochet, reports AFP.

Six human rights groups, including Amnesty International, were to lodge papers with the High Court seeking leave for a judicial review after British Home Secretary Jack Straw said he was "minded" to halt proceedings to extradite Pinochet to Spain to face prosecution.

"Last-minute glitches" scuppered plans to submit the papers Monday before the court closed for the day.

The 84-year-old general is wanted by a Spanish judge to answer charges of human rights abuses during his 1973-1990 dictatorship, when more than 3,000 were killed or disappeared.

Meanwhile Belgium will also be going to the High Court to seek new medical tests on Pinochet, Belgian foreign ministry spokesman Olivier Alsteens said.

A spokesman for Belgian Foreign Minister Louis Michel also said Brussels had instructed a team of British lawyers to prepare a possible application at the International Court of Justice in The Hague.

Straw said on Monday that he would await the results of any judicial review before announcing his final decision.

Amnesty International's lawyer Geoffrey Bindman said a High Court hearing was expected on Wednesday, meaning Pinochet will not learn his immediate fate until Thursday at the earliest. If a review is granted, Straw may have to put off an announcement even longer.

The legal jousting is typical of the saga that has engulfed Pinochet since his arrest in London 15 months ago at the request of Spanish investigating magistrate Baltasar Garzon.

Straw announced he was inclined to release the general after independent medical tests had concluded he was unfit to stand trial. The home secretary has discretionary powers under extradition legislation to allow a release on compassionate grounds, which include health.

Pinochet's sister, Maria Teresa Pinochet, said that when she last saw him, during a trip to London in October, he appeared to have slowed down, but was still mentally sound.

"When I last saw him, I can't say his mind is gone, that would be a lie," she told BBC television late Monday.

"But he is slower. He used to be quick to respond, a fast thinker."

But Judge Juan Guzman, a Chilean judge investigating torture allegations against Pinochet there, told the same programme that he did not believe the general was mentally incapacitated.