Prominent Bahraini rights activist Nabeel Rajab has been re-arrested on suspicion of posting tweets seen as critical of Bahrain's ruling system.
Mr Rajab is accused of publicly insulting residents of a Sunni-dominated neighbourhood for their ties to the ruling dynasty, lawyers said.
The case is the fifth since May against Mr Rajab, who was bailed last week.
Last year, Bahrain cracked down on Shia-led protests against the ruling Sunni al-Khalifa family.
Dozens of people died in the unrest, and rights activists have been routinely prosecuted by the authorities, drawing international criticism.
With 140,000 Twitter followers, Mr Rajab is a high-profile user of the micro-blogging website and a vocal critic of Bahrain's ruler, King Hamad al-Khalifa.
Mr Rajab, a Shia Muslim and head of the Bahrain Centre for Human Rights, was arrested on 5 May but released last week on bail.
He remains on trial in three cases, including for using social networking sites to incite rallies and defaming Bahrain's security forces.
In a hearing on Wednesday, relating to a charge of staging illegal protests, he told the court that all charges against him were "vindictive accusations."
"I was targeted because I was exercising my right to defend human rights, which is a right that is stipulated by the Bahraini constitution," he said.
The hearing was adjourned until 12 June.