Twenty-three Bahraini Shiite opposition activists pleaded not guilty at the start of their trial on Monday to charges of trying to destabilize the government and promoting regime change through terrorism in the tiny Gulf kingdom.

The high-profile hearing follows widespread protests since December by Shiites in this island nation that is a close U.S. ally and hosts the U.S. Navy's 5th Fleet. The rallies have been fueled in part by economic disparities between Bahrain's Sunni ruling elite and the country's poorer, Shiite majority.

The most prominent suspects on trial include opposition leader Hassan Mushaima'a and Shiite cleric Sheik Mohammed Habib al-Moqdad. They were arrested in late January, along with a third defendant, activist Abd al-Jalil Singace who was later released on bail.

The 23 are part of a group of 35 suspects charged with planning to destabilize the government and plotting terror attacks. Twelve other suspects remain at large.

The indictment says the defendants set up "an illegal association that opposes Bahrain's constitution and uses terrorism as a means to achieve its goals" -- a charge that can carry life imprisonment. It also says the defendants "propagated to overthrow the regime and the political system by force" and spread "hatred" of the government. Those charges carry between three to five years in jail.

The defendants claimed in court on Monday that security agents tortured them while in detention. Mushaima'a, who is 61, said the charges were "fabricated" in "revenge" for his political activity.

"These charges are malicious and this trial is a political settling of accounts," he said as he entered his plea.

Al-Moqdad, 47, also rejected the charges and said they meant to "silence political activity and demands" for the rights of the Shiites.

Fourteen lawyers have volunteered to defend the activists. One of the lawyers, Mohammed Ahmed demanded the charges be dropped, the accused set free and allegations of torture investigated.

Defense attorney Jalila al-Sayyid told The Associated Press that she was "extremely concerned" because the court was "not following due process" and hadn't provided the defense with all relevant documents.

"This indicates the judiciary intends to pass political sentences," she said.

Outside the courtroom in Manama, dozens of riot police stood guard as scores of relatives of the defendants crowded around the building to pray for their kin, chant Quranic verses and protest against the trial.

Women clad in head-to-toe black abayas sat on the pavement praying, surrounded by female police officers, while opposition supporters chanted slogans in support of the activists on trial. The courtroom was packed with the suspects' families and Bahraini lawmakers. A French diplomat also attended the hearing, which was open to the public. The trial was later adjourned until 24 March.

In late December, a Bahrain government-controlled TV broadcast what authorities called "confessions" of some of the other defendants, mostly youths said to have been trained in Syria for terror attacks in Bahrain.