A prominent Bahraini human rights activist has been sentenced to three months in jail over comments on social networking websites, his lawyer says.
Nabeel Rajab was arrested last month after prosecutors received complaints that he had libelled residents of the town of Muharraq on Twitter.
He was reportedly taken from his home by masked police after being sentenced.
The case was one of several against Mr Rajab, who has helped organise pro-democracy protests in the Gulf kingdom.
The president of the Bahrain Centre for Human Rights and deputy secretary general of the International Federation for Human Rights has also been a fierce critic of the state's violent crackdown on dissent.
Mr Rajab was detained for three weeks in June while prosecutors investigated complaints that he had "talked on social networks about the people of Muharraq in a way that questioned their patriotism and insulted them".
He wrote on Twitter, where he has more than 155,000 followers, that Prime Minister Sheikh Khalifa bin Salman Al Khalifa should step down, and that Muharraq residents had only welcomed him during a visit because he had offered them subsidies.
Human Rights Watch said it had received information indicating that many of those who had filed complaints were former police and military officers.
It also argued that Mr Rajab's comments concerned political discussion and were therefore clearly protected under his right to free speech.
But on Monday a court found Mr Rajab guilty of libel under the Bahraini penal code and sentenced him to three months in prison. His lawyer had said the most severe penalty in libel cases was usually a fine.
Mr Rajab was also detained in May for accusing the interior ministry of failing to investigate attacks by pro-government gangs on the country's Shia majority community, which has complained of discrimination and led the protest movement against the Sunni royal family, the Al Khalifa.
The Bahraini authorities have accused Mr Rajab separately of inciting "illegal rallies and marches online by using social networking websites".