Bahrain re-arrested leading Shiite rights activist Nabil Rajab on Wednesday pending a probe into tweets deemed insulting to Sunnis, prosecutors said, nine days after he had been freed.
Rajab was "taken into custody pending investigation after he was accused of public insults against plaintiffs" from the predominantly Sunni province of Muharaq, it said in a statement.
The prosecution said it had received complaints that Rajab "talked on social networks about the people of Muharaq in a way that questioned their patriotism and insulted them."
Last year, a significant part of the Sunni community rallied around the government as Shiites led protests against the regime of the ruling Sunni Al-Khalifa family.
Rajab was released on bail last week after he was arrested on May 5, but he remained on trial in three cases, including one for posting comments on Twitter deemed insulting to a government body and two others for protests.
The rights activist was summoned to court on Wednesday to face a new charge of staging illegal protests against Bahrain's ruling family, lawyers said.
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He also received a notice to report to the public prosecution for questioning over the "public insults," according to documents he posted on social networking websites.
Rajab told the court hours before being sent back behind bars 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 to June 12 for "further deliberation," while he should also appear in court on June 17 for other cases.
Rajab led anti-government protests following a brutal crackdown on Shiite-led demonstrations against the regime in March 2011.
The activist has insisted on demonstrating inside Manama, unlike the main Shiite opposition which now stages protests in villages, after last year's clampdown on protesters who occupied the capital's Pearl Square for a month.
The avid tweeter is accused of insulting the security forces in postings that he admitted came from his account own on the microblogging website.
Bahrain came under strong criticism from international rights organisations over last year's crackdown on demonstrations that were inspired by the Arab Spring uprisings.