DUBAI: A court in Bahrain Tuesday jailed 36 Shiites convicted of forming a “terrorist” group to attack police, and stripped them of their citizenship, a judicial source said. Three of those sentenced received life terms, while the rest were jailed for between three and 10 years, the source said.

The defendants had been charged with “forming an illegal group that aimed to jeopardize the constitution and laws ... using terrorism as one of its means,” according to the judicial source.

They were also accused of “possessing explosives without permits,” the source said, adding that the defendants confessed to taking part in riots and vandalism.

The kingdom has been the scene of frequent protests and clashes with police since security forces quelled Shiite-led nationwide protests in 2011 that called for political reforms.

Hundreds of Bahrainis have been arrested and several high-profile figures, including a Shiite preacher, stripped of citizenship.

Amnesty International Tuesday accused authorities of “dramatically” escalating the crackdown on perceived critics, with 32 people summoned by the public prosecution within five days.

The rights group said that at least 24 have since been charged with “illegally gathering.”

The measures come ahead of Bahrain’s U.N. human rights review session in Geneva on May 1, Amnesty said, adding that the timing “strongly suggests that this is part of a deliberate attempt to prevent peaceful critics from speaking out about the government’s record in Geneva.”

Amnesty said those summoned included lawyers, rights and political activists and relatives of “victims of human rights violations.” Eight of those charged were told they are banned from traveling, and four have so far been prevented from leaving the country, Amnesty said.