Police arrested an activist after he criticised the United Arab Emirates' security services for interfering in the lives of citizens, the latest step to limit political dissent in the major oil exporter.
Saleh al-Dhufairi was taken from his home in the northern emirate of Ras al-Khaimah early on Tuesday after posting comments via Twitter attacking the UAE's decision to deport Syrian expatriates who demonstrated outside their consulate in Dubai without a permit.
"Saleh al-Dhufairi has been arrested on accusation of spreading ideas by speech, writing and any other means that provoke strife, hurt national unity and social peace," a spokesman for Dubai police said in a statement.
The UAE has avoided the kind of pro-democracy protests that have convulsed other countries in the region. It has tolerated little dissent during the upheaval that resulted in the ouster of rulers in Tunisia, Egypt, Libya and Yemen.
Dhufairi's brother-in-law, Mohammed al-Mansouri, said plain-clothes policemen arrived in unmarked cars at night and arrested him without a warrant. He initially refused to accompany them, but later agreed.
Police told the family an arrest order had been issued by the electronic crimes department in the emirate of Dubai. Dubai police said Dhufairi would be tried in a federal court.
"The people want the liberation of civil life from the chains of the security services," Dhufairi wrote on Twitter, singling out its interference in religious affairs.
Rights groups have criticised the UAE for the expulsion of some Syrians following a demonstration in Dubai last month against President Bashar al-Assad's rule.
A UAE official had said authorities decided not to renew the residency permits of around 30 Syrians who had refused to disperse after an unlicensed demonstration ended peacefully.
Mansouri said his brother-in-law had begun to use Twitter after the UAE revoked the citizenship of six Emirati activists in December on charges they posed a threat to national security.
Five other political activists were also convicted and then pardoned last year on charges of insulting the UAE's leaders, inciting protests and disrupting public order.