Bahrain should immediately release a group of opposition activists detained for petitioning the Gulf state's government for more democratic reforms, a human rights watchdog said on Tuesday.
Human Rights Watch said in a statement that the arrest of 19 activists was a "blatant suppression of freedom of speech and association" that flies in the face of reforms undertaken by the pro-Western government.
"The right to petition peacefully is fundamental, and this petition addresses an issue that lies at the heart of democratic reforms," said Sarah Leah Whitson, head of Human Rights Watch's Middle East and North Africa Division.
The 19 were detained earlier this month for signing a petition demanding constitutional changes to give more power to the country's elected parliament, which is on equal footing with a chamber appointed by the king.
Eleven are still in custody after the others were released on bail.
Bahrain, the Gulf's banking hub and home of the US Navy's Fifth Fleet, has introduced some reforms but the opposition, led by the country's majority Shia Muslims, want more rights in the Sunni-ruled island state.
The government says any changes to the constitution, which was overwhelmingly approved by Bahrainis during a referendum, must be instigated by the king, who has broad powers by law.
The activists, mainly aged between 18 and 25, are being held without bail. They face charges of trying to destabilise public security, which carries a penalty of life in prison.