Belgium and six human rights groups have failed in the latest attempt in a long-running battle to prevent the release of General Augusto Pinochet.

A High Court judge rejected their application for judicial review, after it was proposed that the former dictator be freed from house arrest in the UK.

Belgium said it was disappointed by the decision and lodged papers to renew its legal challenge before the Divisional Court shortly afterwards. A hearing before three or four judges will be held on Monday.

Belgium's decision could mean General Pinochet must spend at least another week in Britain.

UK Home Secretary Jack Straw has said that when he makes his final decision on the case, he will announce it in parliament. A Home Office spokesman said no date had been set for this announcement.

Amnesty International also said it was considering whether to renew its legal challenge.

Mr Straw has said he is "minded" to release the general after a panel of medical experts decided he was unfit to stand trial.

The protesters had argued that Mr Straw's decision not to release the medical report on the former Chilean leader's health was unfair and unlawful, insisting it undermined their case.

But in the latest ruling on the case, Mr Justice Maurice Kay said he was "completely against" the argument to disclose the report, saying the application "must be refused".

The judge added that Mr Straw had already obtained an "impartial" medical assessment of general Pinochet by an internationally respected team of clinicians.

Human rights campaigners said they were "profoundly disappointed" at the judgement.

Helen Bamber, director of the Medical Foundation for the Care of Victims of Torture, said: "We are considering an appeal. Mr Straw has still to respond to representations asking for the general's medical report to be made available."

The challenge in the High Court had been made on three grounds:

• The procedures used by the Home Secretary to reach his decision were not fair.
• There was a failure to disclose details of the medical reports meaning parties were not able to challenge the findings.
• Concern over the choice of experts to conduct the medical tests on the general.

During the hearing, Presiley Baxendale QC, appearing for Belgium said Mr Straw's refusal amounted to "a breach of natural justice".

But Jonathan Sumption QC, for the home secretary, insisted Mr Straw had promised to keep the medical reports confidential and said enough information had been released to let the parties put forward their views.

He also said the Belgians had not thought their arguments through and accused them of launching a "diatribe" against Mr Straw's decision.

Jet on stand-by

General Pinochet has been fighting extradition to Spain since he was arrested more than a year ago after coming to the UK for medical treatment.

The long-running proceedings have already claimed a prominent place in English legal history.

While under house arrest he was visited by former Prime Minister Margaret Thatcher, who called for him to be allowed home saying Chile had been an ally of the UK during the Falklands War.

A Spanish judge made the extradition request to the UK, alleging General Pinochet had committed crimes against humanity while in charge of Chile's military government from 1973 to 1990.

The six human rights groups involved are Amnesty International, Human Rights Watch, the Medical Foundation for the Care of Victims of Torture, the Redress Trust, the Association of Relatives of the Disappeared and Justicia.

Belgium entered the dispute after allegations that General Pinochet was behind the jailing and killing of Chileans whose relatives now live in Belgium.

A Chilean air force jet is waiting at RAF Brize Norton to take the former dictator home as soon as he is allowed to leave the country.

He will remain under house arrest on the Wentworth Estate in Surrey until the case is finally resolved.