Updated

Bahrain's King Hamad has decreed stiffer penalties for "terror acts" in the country rocked by a Shiite-led uprising since 2011, the official BNA news agency said Thursday.

Under a new law, suspects convicted for bomb attacks will be sentenced to life imprisonment or to death in cases of casualties, BNA said. The minimum penalty for an attempted bombing is 10 years behind bars.

The crimes previously carried unspecified jail terms.

Suspects found guilty of "raising money for a terrorist organisation" will be handed jail terms ranging 10 years to life.

Authorities will also have powers to revoke the citizenship of anyone found guilty of committing or inciting an act of terrorism.

Tensions have been on the rise in the Sunni-ruled but Shiite-majority Gulf kingdom ahead of a major opposition demonstration called for mid-August.

Authorities have already decided to ban the protest and threatened to severely punish those who take part.

On Monday, King Hamad ordered the government to implement a parliamentary call for tough measures against what the authorities term an upsurge in "terrorism" linked to the Shiite-led protests.

At a special session requested by the king during a parliamentary recess, mostly loyalist MPs also recommended "a ban on gatherings and rallies" in the capital Manama.

They called for emergency law to be declared in the Gulf state if the need arose.

Amnesty International warned Wednesday that the adoption of the amendments would "lead to further violations of Bahrain's international human rights obligations."

The Shiite-led opposition has condemned the language used in the parliamentary debate as a "declaration of war on the people, as well as open threats and insults to beliefs".

But opposition groups insisted in a statement that the people's actions remain "peaceful," denouncing "propaganda to promote a security solution... which violates international conventions".

The authorities report a growing number of shootings and bombings targeting police stations and patrols in Shiite villages outside Manama, blaming "terrorists" for the attacks.

On Thursday, a criminal court sentenced 12 Shiite protesters to two years in prison each for taking part in "unlicenced protests" and targeting "police forces with Molotov cocktails," a judicial source said. Eight of them were tried in absentia.

Shiite demonstrators have kept up pro-democracy protests despite a 2011 crackdown backed by Saudi-led Gulf troops, sparking repeated clashes with security forces.

A car bomb on July 17 exploded outside a Sunni mosque, close to the royal court in Rifaa south of Manama, without causing any casualties. There have since been three arrests.

At least 80 people have been killed in Bahrain since protests erupted two years ago, according to the International Federation for Human Rights.

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