A jailed rights activist in Bahrain has gone back on hunger strike ahead of the 14 February anniversary of a pro-democracy uprising, the Bahrain Youth Society for Human Rights said on Thursday.

Abdulhadi Al-Khawaja was one of 14 prominent figures, convicted of leading the protests, who took part in an eight-day hunger strike to demand their release. Bahraini authorities said that hunger strike ended last week.

"Al-Khawaja said in a telephone call to his family, freedom or death, which means he started an open hunger strike until his release," said the Bahrain Youth Society for Human Rights on its website.

The opposition is trying to sustain pressure on the government, dominated by the Sunni Muslim Al-Khalifa family, ahead of the anniversary of the uprising. The reforms they want include an elected government - the first in the Gulf - and reduced powers for the Al-Khalifa family.

Bahrain imposed martial law in March last year and asked troops from Saudi Arabia and the United Arab Emirates to help crush the month-old uprising.

The government said the island's majority Shia Muslims had coordinated the protests with Iran for sectarian reasons, an accusation the opposition has denied.