Bahrain Mirror (AFP): A Bahraini appeals court Tuesday upheld death sentences for three Shiites convicted of killing three policemen in a bombing in the Sunni-ruled Gulf kingdom in 2014, a judicial source said.

The court also upheld life sentences for six other defendants convicted over what was the deadliest attack on security forces since a Shiite-led uprising was crushed in 2011.

A seventh defendant previously sentenced to life in jail did not appeal because he remains at large, the judicial source said.

A policeman from the United Arab Emirates was among the three officers killed in the Shiite village of Diah in March 2014.

He was the first foreign officer killed since Saudi-led troops and police were deployed to Bahrain to support its crackdown on the Arab Spring-inspired protests.

Bahrain, which lies across the Gulf from Shiite Iran and is home to the US Navy's Fifth Fleet, has been rocked by unrest since it quelled Shiite-led protests demanding political reforms in 2011.

On Monday, a Bahraini court more than doubled the jail sentence against opposition leader Sheikh Ali Salman, in a ruling his bloc warned risked stoking fresh unrest.

The appeals court increased the sentence of the Shiite cleric on charges of inciting violence to nine years from the original four.