MANAMA A Bahraini court sentenced two men to life in prison and two others to 15 years for a car bomb attack outside a mosque in July, state news agency BNA said on Sunday.
Bahrain, a Western ally which hosts the U.S. Fifth Fleet, has been in political turmoil since a 2011 uprising led by majority Shi'ites. They demand reforms and more share in running the kingdom, which is ruled by the Sunni Muslim al-Khalifa dynasty.
Several vehicles were destroyed but no one was hurt in the explosion outside a Sunni Muslim mosque in al-Riffa, south of the capital Manama, where some members of the royal family live.
Government officials said at the time the attack, which took place during evening prayers in the Muslim holy month of Ramadan, was an attempt to inflame sectarian tensions.
Among other charges, the defendants were convicted of setting up and joining an organization "that uses terrorism as a means to achieve its aims", setting off an explosion to terrorize innocent people, stealing cars and training to make explosives, BNA said.
The authorities have quelled the revolt in the island kingdom, which sits between Sunni-ruled Saudi Arabia and Washington's main regional antagonist, Shi'ite power Iran.
But protests and small-scale clashes continue, and bomb attacks have been increasing since mid-2012. At least one policeman was killed and five security officers were wounded by explosions and homemade bombs in recent months.
Bahraini Shi'ites complain of discrimination in areas such as jobs and public services - something the government denies. Talks between the government and opposition have failed to end the political crisis.
(Reporting by Farishta Saeed; writing by Rania El Gamal; editing by Sami Aboudi and Mark Trevelyan)