"The defense presented a motion during the court hearing today clarifying the difficulties the lawyers have faced in carrying out their mission in addition to abuses that need to be investigated and the poor conditions under which the accused are detained," Mohammed Al-Tajer said.

"We made clear to the court that we are not able to continue our mission under these conditions, and we withdrew," he said.

The court decided to appoint new attorneys to represent the activists and adjourned the trial until Dec. 23, said Al-Tajer.

The 25 activists, including two who are being tried in absentia, are accused of forming an illegal organization, engaging in and financing terrorism, and spreading false and misleading information, according to the indictment.

Some of the charges carry a sentence of life in prison, one of the lawyers has said.

At the opening hearing on Oct. 28, the 23 defendants appeared in court and pleaded not guilty, while alleging they had been tortured.

The court declined at that hearing to probe the allegations, but a government statement the same day said a "senior forensic science consultant" had examined 13 defendants and concluded they had not been tortured.

Al-Tajer said lawyers had renewed calls for an investigation at the second hearing on Nov. 11.

He also said at the time that "certain decisions of the court, including the transfer of the defendants from a state security prison to an ordinary one, have not been implemented."

Another defense attorney, Jalila Al-Sayed, said the 25-member legal team walked out after failing to get a court-ordered probe into alleged jailhouse beatings and other abuses against the suspects, who include human rights activists and bloggers.

"We withdrew because the court disregards our requests to investigate the torture claims," said Al-Sayed. "We now consider this trial to be unfair and against international standards and we won't be part of it."

In the 1990s, Bahrain was plagued by a wave of opposition unrest that has abated since 2001 reforms restored the Gulf state's elected Parliament, which was dissolved in 1975, and turned the emirate into a constitutional monarchy.

Parliament's powers were diluted, however, with the formation of an appointed upper house.

The walkout was the latest tactic to draw attention to prisoner abuse claims and force a deeper look into a major crackdown on dissidents in the kingdom that hosts the US Navy's 5th Fleet.

The arrests of the activists were part of a sweeping offensive launched last summer against threats to the state. The detentions touched off riots and rallies that have severely strained relations between rival communities in the country.

Washington and allies worry that the widening rifts could roll back a decade of political reforms and open footholds for outside powers.