Bahrain Mirror (AFP): A court in Bahrain on Monday added 15-year jail terms to the sentences of 57 Shiite inmates involved in a prison mutiny, a judicial source said.

The inmates were convicted of rioting and mutiny following unrest last March at Jaw prison south of the capital Manama, the source said.

The charges included "disobeying orders and forcing guards out of the prisoners' buildings" and then "destroying furniture, air conditioners and security cameras", the source said.

Security forces finally stormed the buildings and clashed with the rioting prisoners, resulting in casualties among police and inmates, the source added.

Al-Wasat newspaper said the defendants were also fined a total of 508,187 dinars ($1.35 million).

It was not clear what caused the riot in Bahrain's largest prison that is used for Shiites convicted over anti-government protests.

Human Rights Watch called last May for an independent investigation into allegations that security forces used "excessive force" to quell the unrest at the jail and later mistreated prisoners.

Bahrain's Sunni authorities crushed Shiite-led protests a month after they erupted on February 14, 2011.

The strategic Shiite-majority, Sunni-ruled kingdom lies across the Gulf from Shiite Iran and is home to the US Fifth Fleet.