A Bahraini court has sentenced two Shia Muslims to death and jailed 56 others on charges of "terrorism", prosecutors in the Sunni-ruled Gulf kingdom have said.

The supreme criminal court also stripped 47 of the defendants of their Bahraini citizenship at Wednesday's mass trial, accusing them of "forming a terrorist group" to carry out "murders" and "attacks" against police officers, a statement on the state news agency BNA said.

According to the public prosecution, some of the defendants were also charged with training to use weapons and possessing bombs.

Of the 60 Bahrainis who were prosecuted at the closed-door hearing, 19 were sentenced to life in prison, 17 were given 15 years, 9 were handed 10 years and 11 were given 5 years.

Only two were acquitted, it said.

Responding to the ruling, Sayed Ahmed Alwadaei, director of advocacy at the Bahrain Institute for Rights and Democracy (BIRD), called it a "travesty of justice".

"Authorities have further proved their willingness to exploit the vulnerability of its citizens: the lives of two men hang in the balance; women are being subjected to harsher sentences of imprisonment; and the overwhelming majority of those whose citizenship has been revoked are rendered stateless.

"Coerced confessions have become the norm for Bahraini courts in their deliverance of suffering to its citizens."

Tensions have been running high in Bahrain, where there is a growing gap between the Sunni-led government and the island's Shia population.

Bahrain's Saudi-backed authorities crushed the Arab Spring protests shortly after they erupted on February 14, 2011, and have refused to listen to opposition demands for reforms.

Human rights groups have accused Bahrain of clamping down on dissent and violently cracking down on protests.

The government says the protesters are supported and influenced by Iran, but activists insist they are fighting for jobs, housing, and political clout.