Prominent Shiite activist Nabeel Rajab was Tuesday sentenced to six months in prison after a Bahraini court found him guilty of insulting public institutions in his tweets, a judicial source said.
But Rajab, who was released from custody one month after his arrest in October 1, could stay out of prison on bail if he pays 200 dinars (530 dollars), the source told AFP, citing the court ruling.
The prosecution, in a statement, said the ruling is subject to appeal.
Rajab, a member of Bahrain's Shiite majority which has held protests against the kingdom's Sunni rulers since 2011, was arrested after posting Twitter comments about the interior and defence ministries.
In one of the tweets deemed offensive, Rajab charged that many Bahrainis fighting with jihadists in Syria were former  Bahraini security forces personnel who had developed Sunni extremist views while in service.
Rajab, who has led anti-government marches and heads the Bahrain Centre for Human Rights, was freed last May after serving two years in jail for taking part in unauthorised protests.
His new conviction came one day after prosecutors charged Bahrain's Shiite opposition chief Sheikh Ali Salman with attempting to overthrow the regime and set a January 28 trial date.
International rights groups have condemned the trials against opponents of the Sunni regime ruling the Gulf state.
Human Rights Watch and the Gulf Centre for Human Rights on Friday urged Bahrain's Western allies to pressure the kingdom to drop charges against Rajab, saying he should have never been charged.