Updated

A rights activist in Bahrain says a court has sentenced 50 people to prison terms of between five and 15 years after a mass trial for alleged links to a militant group blamed for bombings and other anti-government attacks in the Gulf nation.

The convictions Sunday mark the broadest blow yet against suspected backers of the February 14 faction, named after the date in 2011 that began an uprising by Bahrain's Shiite majority seeking greater political rights from Sunni rulers.

But the verdicts could stir more unrest in the kingdom, home to the U.S. Navy's 5th Fleet.

Mohamed al-Maskati, head of the Bahrain Youth Society for Human Rights, said 20 suspects were convicted in absentia. Charges included seeking to topple the ruling system.

Hundreds have been arrested in Bahrain's crackdowns.