DUBAI (Reuters) - Prominent Bahraini opposition activist Nabeel Rajab was sentenced to three years in jail on Thursday for anti-government protests, his lawyer said, a verdict likely to undermine a U.S. call for dialogue to defuse political tension on the island.
Bahrain, a U.S. ally and base for the U.S. Navy's Fifth Fleet, has been in turmoil since pro-democracy protests led by its Shi'ite Muslim majority erupted last year after successful revolts in Egypt and Tunisia.
Rajab is the founder of the Bahrain Centre for Human Rights and has led many protests against the wide powers of the Sunni Al Khalifa dynasty which rules the island kingdom.
A hero to protesters, but villain for Bahrainis who fear the protests will bring Shi'ite Islamists to power, Rajab is already serving three months in jail over a tweet criticising the veteran prime minister. A court said it insulted Bahrainis.
The judge ruled in three cases on Thursday, all related to participating in peaceful protests, and handed down a one-year jail sentence in each, Rajab's lawyer Mohammed al-Jishi said, adding that he plans to appeal the ruling.
"It is a very stiff and unexpected ruling, I am surprised. They are peaceful protests, not violent ones," Jishi said.
Others found guilty in similar cases, he said, were sentenced to a maximum of six months in jail and some were freed on bail.
Rights groups sharply criticised the sentence.
"This is a shocking verdict, even by Bahrain's own abysmal standards on human rights. The regime can't be seen serious about human rights reform when it jails one of the world's most prominent activists to prison for three years," said Brian Dooley of U.S.-based Human Rights First.
There has been little progress towards opposition demands for reforms including a parliament with full powers to legislate and form governments. Many Shi'ites complain of political and economic marginalisation, a charge the government denies.
Bahrain has increased parliament's powers of scrutiny over ministers and says it is reforming policing to conform with international rights standards. It accuses protesters of rioting and wounding police.
While uprisings ended with long-standing governments overthrown in Egypt, Tunisia, Yemen and Libya, Bahrain imposed martial law to try to crush the protests there last year.
Washington has urged Manama to hold a dialogue with the opposition to end the unrest and hold officials accountable for rights violations uncovered in an investigation led by international legal experts published in November.
But the United States values close ties with the ruling family, which allows Washington to run its Fifth Fleet operations out of Manama.
The fleet plays a key role in ensuring the free flow of oil in the Gulf while Tehran has threatened to stop shipping in vital shipping lanes nearby if the United States steps up pressure over Iran's disputed nuclear programme.
On Tuesday, a court delayed until September 4 a ruling in the retrial of 20 men convicted of leading the uprising, and since June the government has banned a series of protest rallies planned by leading opposition party Wefaq.
Reporting by Rania El Gamal and Andrew Hammond; Editing by Jon Hemming