The Syrian government is ordering politically sensitive text messages to be blocked with technology from an Irish firm being used to implement the orders, according to two people familiar with the filtering systems.
A unit of the Syrian intelligence apparatus, known as "Branch 225", often issues the instructions on which messages to block, according to the sources.
Syriatel Mobile Telecom, the country's largest mobile-phone operator, conducts the blocking with equipment from Cellusys Ltd, a privately-held company based in Dublin, according to one of the people, who is familiar with the filtering.
Cellusys delivered a filtering system to Syriatel in 2008 as the mobile operator struggled to combat viruses and spam, which can be blocked by such technology, according to Cellusys chief executive Dawood Ghalaieny.
Syriatel is controlled by Rami Makhluf, cousin of Syrian president Bashar al-Assad, according to the US Department of the Treasury, which enacted sanctions against the company last year.
In addition, another Irish company, AdaptiveMobile Security, has supplied message- filtering technology to MTN Syria, the country's second-largest mobile operator.
While AdaptiveMobile executives declined to comment, in interviews last year concerning the sale of its product to a mobile operator in Iran, they said its technology is for blocking spam, viruses and inappropriate content, not political repression.
The sales by Cellusys and AdaptiveMobile were legal. The European Union tightened restrictions last year on sales of equipment to Syria that can be used for internal repression, however it's unclear whether the software is prohibited by the new rules.
The filtering of text messages has curbed the protesters' ability to use technologies that helped organise and fuel dissent in other countries across the Middle East and topple autocratic regimes in Tunisia, Egypt and Libya, according to political opposition groups.
Cellusys says it has not sent workers to Syria since 2009 and is not sure how its technology is being used today
In response to questions sent by email, AdaptiveMobile chief executive Brian Collins replied in writing that Bloomberg's information was incorrect without providing specifics.
AdaptiveMobile executives did not respond to follow-up inquiries.
Bloomberg