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 on Tuesday, citing the court ruling.
The prosecution, in a statement, said the ruling is subject to appeal.
Rajab was arrested after posting Twitter comments about the interior and defense ministries.
In one of the tweets deemed offensive, Rajab charged that many Bahrainis fighting with Takfiris in Syria were former Bahraini security forces personnel who had developed 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 protests.
His new conviction came one day after prosecutors charged Bahrain’s 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 regime ruling the Persian 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.
