The suspects — 14 in custody and the others charged in absentia — are accused of attempting to overthrow the government and of having links to “a terrorist organization abroad.”

Authorities are seeking to prosecute opposition leaders and others after months of clashes and protests in Bahrain, which hosts the US Navy’s 5th Fleet.

The 21 accused are being tried in a special security court set up under martial law. Last month, the court sentenced four people to death for killing two policemen during the unrest.

Among those on trial are Hassan Mushaima, the leader of Al-Haq movement. He was among the first opposition leaders arrested after emergency rule was declared in March to restore order after weeks of anti-government protests.

Mushaima returned from self-imposed exile in late February and immediately joined in street protests that were inspired by revolts against autocratic leaders in Tunisia and Egypt. He and fellow Al-Haq member Abdul Jalil Al-Singace were among 25 activists on trial last year on charges of trying to overthrow the government.

Also on trial are Abdulhadi Al-Khawaja, the country’s most prominent human rights activist; Ibrahim Sharif and Ali Abdul Emam, a blogger and founder of a popular discussion forum Bahrain-On-Line.

The defendants have entered not guilty pleas. The trial resumes Sunday.

The Bahrain News Agency also said on Monday the court has agreed to end solitary confinement for opposition leaders detained in March.