A court in Bahrain sentenced six people on Wednesday to life in prison after finding them guilty of involvement in a plot to kill police officers with explosives.

The six, two of whom were tried in absentia, were found guilty of attempted murder and possession of explosives in a Shia village near Manama in May 2015, prosecutors said in a statement.

They said the explosives were discovered in Al-Maamir before they could be detonated.

Bahrain has been shaken by unrest since security forces crushed Shia-led protests demanding a constitutional monarchy and an elected prime minister in 2011.

Despite repeated calls from their Western allies, Bahrain's Sunni rulers have made no concessions to the Shia opposition and have intensified a crackdown on critics.

Scores of Shias have been jailed on charges of involvement in the unrest and others have been stripped of their citizenship.

The crackdown has drawn criticism from the United Nations and the United States.