Hackers have published the contact information of thousands of customers of San Francisco's mass transit system after the transit agency blocked cell phone service in some stations to prevent a protest.

The group Anonymous posted the names, addresses, phone numbers and email addresses of about 2,000 people on its own site Sunday after taking the information from a marketing website used by the transit service.

The hackers are protesting what they say is a curb on free speech, saying they will not “tolerate oppression from any government agency.”

The transit agency shut down cell phone service in some of its stations last Thursday, in an attempt to prevent a protest over the shooting death of a knife-wielding homeless man by police last month.

The agency says its main website was not affected by the hackers, and has warned riders that protesters may try to disrupt Monday's evening commute.

Anonymous said earlier this month it had hacked into the websites of about 70 U.S. law enforcement agencies in retaliation for the arrests of some of its supporters.

The U.S. Federal Bureau of Investigation and British and Dutch officials last month arrested 21 people, with many of the apprehensions related to the Anonymous attacks on the Internet payment company PayPal. It was targeted because PayPal has refused to process donations to WikiLeaks, the group headed by Australian Julian Assange that has divulged thousands of sensitive documents lifted from the computer files of U.S. diplomatic and military operations.