Authorities in Bahrain charged 25 Shiite Muslim activists with plotting against Sunni rulers on Thursday after months of harsh crackdowns that have deeply shaken one of the most strategic U.S. allies in the Gulf.

The suspects pleaded not guilty and many immediately complained about alleged torture behind bars in a sign of combative atmosphere for the trial, opening less than a week after highly charged parliamentary elections in the tiny island kingdom that hosts the U.S. Navy’s 5th Fleet.

Washington and its allies are seeking ways to ease tensions between the majority Shiites, who claim widespread discrimination, and the ruling Sunni dynasty which sees itself as under siege and facing possible proxy threats from Shiite heavyweight Iran.

Bahrain has been hit by sporadic unrest for decades as Shiites, who represent 70 percent of the nation’s 530,000 citizens, press for a greater political voice and opportunities. Political reforms, including parliamentary elections, in the past decade have opened more room for Shiites. But they complain the Sunni—directed system still excludes them from any key policymaking roles or top posts in the security forces.

The trial is likely to further boost suspicions and anger on both sides.

The group is accused of supporting “terrorist” cells seeking to overthrow the ruling system. The original 23 suspects, whose names were splashed across state media last month, were unexpectedly joined by two other defendants, including a prominent blogger.

The level of concern by authorities was evident in the blanket security around the court in Bahrain’s capital Manama, including anti—riot police and helicopter surveillance. Only one family member for each suspect was allowed in the court gallery alongside observers that included U.S. diplomatic envoys and rights groups.

The proceedings were covered by Bahrain’s state television, but reporting restrictions were placed on other local journalists.

The latest backlash from authorities began in August with the arrest of several prominent Shiite right activists. Shiites responded with street riots and wildcat protests. More than 250 people have been detained and several blogs and other media outlets have been silenced.

One of the lawyers for the alleged coup plotters, Mohamed al—Tajer, said he has received reports from families of abuses including beatings and round—the—clock interrogations. Bahraini officials deny any of the detainees have been mistreated.

One of the suspects entered court with what appeared to be bandages on one leg. The reason was not immediately clear.

The original group of 23 includes prominent rights activist Abdul—Jalil al—Singace, who was taken into custody on August 13 as he returned from London with his family. The other alleged coup plotters range from professors, taxi drivers and a dentist, all facing possible life sentences if convicted.

The other two suspects include a Shiite political figure and blogger Ali Abdulemam, whose case has been taken up by media freedom groups.

In Bahrain’s parliamentary elections last week, Shiites held onto their 18 seats in the 40—member chamber but are not expected to gain enough allies for a majority. The second round of voting is Saturday.

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