International rights groups are urging Bahrain to stop all proceedings before a special military tribunal amid allegations the proceedings are politically motivated and defendants arrested during anti-government protests were tortured.

U.S.-based Human Rights Watch said Tuesday most of the court's convictions are for “blatantly political charges” such as participating in unauthorized demonstrations and “incitement of hatred against the regime.”

Separately, Amnesty International called on Bahraini authorities to immediately open an independent investigation into allegations of torture and throw out any confessions extracted under duress.

Both groups are concerned with the fate of a prominent lawyer, Mohamed al-Tajer, who was taken from his home in April and brought before the tribunal on Sunday, along with other defendants. The government has refused to provide information about where al-Tajer is being detained or his well-being.

Opposition groups have said hundreds of people are on trial, in what they call a revenge move by Bahrain's Sunni rulers after having violently put down anti-government protests in March led mostly by the country's majority Shi'ite population.

The Sunni royal family accuses demonstrators of being motivated by sectarianism and supported by Iran.

The trial of 48 medical professionals resumed Monday following earlier complaints that lawyers did not have sufficient access to their clients. Several doctors pleaded not guilty to a range of charges including seizing control of a hospital during recent anti-government demonstrations, storing weapons and keeping people prisoner.

Many of the defendants worked at the Salmaniya Medical Complex, which the government says served as a coordination point for the Shi'ite-led protests.

A number of doctors who attempted to tell the judge their confessions had been extracted under torture were silenced.

During Monday's hearing, defense lawyers asked for civilian doctors to examine their clients, who have only been seen by military medical staff to date. The judge agreed, and adjourned the proceedings until next week.

Bahrain says it has detained the medical workers since March. Western media reported they were formally charged last Monday.

Bahraini officials say 24 people died in the unrest early this year, and the Sunni-led government arrested hundreds in the aftermath of the uprising.