Hacktivist group Anonymous has stolen thousands of user records from the San Francisco’s public transport provider after it blocked mobile communications in an attempt to prevent a riot.

Fearing that a protest following a police shooting might erupt into violence, officials at the Bay Area Rapid Transport (BART) system successfully requested that mobile telecommunication carriers block services at four train stations in San Francisco.

The move took place just as politicians in the UK were discussing the prospect of blocking social networks to prevent further rioting, and drew heavy criticism from freedom of communications groups. The Electronic Freedom Frontier compared the act to when former Egyptian president Hosni Mubarak’s blocked mobile telecommunications during the Egyptian revolution earlier this year.

In retaliation, hacktivist group Anonymous infiltrated one of BART’s websites, stealing thousands of user account details, including email addresses, passwords, home addresses and telephone numbers, and publishing them online.

"We apologise to any citizen that has his information published, but you should go to BART and ask them why your information wasn’t secure with them," a statement purpotedly from the group says. "Also do not worry, probably the only information that will be abuse from this database is that of BART employees".

Observers haved pointed out that Anonymous’ actions have only added to the number of BART customers whose rights have been infringed. "It is puzzling to me how exposing thousands of innocent people’s personal information hurts BART more than it hurts transit users," wrote Chester Wisniewski, a senior advisor at security firm Sophos, on the company’s blog.

In other Anonymous news, yesterday the group called for a day of mass protests in the UK on October 15th.