A Bahraini court on Wednesday sentenced six tweeters charged with insulting King Hamad to one year in prison, the public prosecutor's office announced.
The six were charged by the lower criminal court with "misusing the right of free expression," it said in a statement.
They were accused of writing remarks "undermining the values and traditions of Bahrain's society towards the king on Twitter," according to the statement.
Activists in Bahrain, scene of a Shiite-led uprising that began two years ago against the ruling Sunni monarchy, use Twitter as a platform to report what they describe as regime "violations" against them.
"Free expression is a right adopted by law ... but must be practised objectively away from insults and undermining values," the statement read.
Prominent activist Nabil Rajab, who heads the Bahrain Centre for Human Rights, was arrested last year on charges of insulting members of the Sunni community via Twitter.
The avid tweeter was also accused of insulting the security forces in postings that he admitted came from his account on the microblogging website.
He was cleared of the charges on August 23.
A total of 80 people have been killed in Bahrain since the protests erupted in February 2011, according to the International Federation for Human Rights.
Strategically located just across the Gulf from Iran, Bahrain is home base to the US Navy's Fifth Fleet and is also a major offshore financial and services centre for its Arab neighbours in the oil-rich Gulf.