Bahraini human rights activist Nabeel Rajab, one of the most outspoken critics of country's government, has been sentenced to three years in prison for leading anti-government protests last year.

Bahrain, a U.S. ally and base for the U.S. Navy's Fifth Fleet, has seen a year of unrest and protest suppression since pro-democracy protests led by a Shi'ite Muslim majority erupted last year following the revolts of Egypt and Tunisia.

Rajab, founder of the Bahrain Center for Human Rights, led many of the country's protests and is already serving three months in jail over a tweet criticizing the prime minister.

Amnesty International has identified Rajab as a prisoner of conscience.

"The court's decision is a dark day for justice in Bahrain that further questions the independence of the judiciary. Like many others in Bahrain, Nabeel Rajab is a prisoner of conscience, jailed solely for peacefully exercising his right to freedom of expression and assembly. He should be released immediately and his convictions and sentences quashed," Amnesty stated today.

The Bahraini government imposed martial law last year in an attempt to quell the country's uprising, but has received pressure from world powers to compromise with the pro-democracy protesters, put an end to the unrest and hold officials accountable for rights violations. But the US maintains close ties with the ruling family, which allows it to operate out of Manama -- a key position in the Gulf oil trade.

Rajab's wife Sumaya, who was with him at the reading of the verdict, told Amnesty International:

"The sentence, although harsh and unfair, comes as no surprise to Nabeel and I. It shows how biased and corrupt the judiciary in Bahrain is. There are no human rights in Bahrain. As the defense team said, this sentence is the biggest scandal in the history of Bahrain judiciary."