A Bahraini court Thursday sentenced 18 Shias to between five and seven years in prison after they were convicted of attacking a police station, a judicial source said.

Fifteen defendants were jailed for seven years and three for five years after being convicted of attacking the police station in a Shia village near Manama last November.

They had been charged with "aggression" against the police, "possession of petrol bombs" and taking part in an unauthorised protest "aiming at undermining public security."

No casualties were reported in the attack.

Thursday's ruling brings to 122 the number of Shias jailed since 29 September in connection with violence in the Sunni-ruled Gulf kingdom that began in February 2011 with a month-long uprising.

In August, King Hamad decreed stiffer penalties for "terror acts."

These include a minimum 10-year jail term for an attempted bombing. If such attacks cause casualties, the sentence can be life imprisonment or the death penalty.

Bahraini Shias continue to demonstrate in villages outside the capital and frequently clash with police.

At least 89 people have been killed since the protests began two and a half years ago, according to the International Federation for Human Rights.

Strategically located across the Gulf from Shia Iran, Bahrain is home to the US Navy's Fifth Fleet and is an offshore financial and services centre for oil-rich Arab neighbours.