Britain's prime minister threatens to act against press over NSA surveillance leaks

British Prime Minister David Cameron walks past a sign prohibiting the use of mobile phones, after he addressed the media at the European Council building in Brussels, Friday, Oct. 25, 2013. Migration, as well as an upcoming Eastern Partnership summit, tops the agenda in Friday's meeting of EU leaders. (AP Photo/Yves Logghe) (The Associated Press)

British Prime Minister David Cameron has threatened unspecified action over the Guardian newspaper's remarkable disclosures of American intelligence material, saying officials would find it tough to stand back if the media don't show enough restraint over what they publish.

Although Britain has no First Amendment-like protection guaranteeing freedom of the press from official interference, governments have generally relied on informal lobbying to keep sensitive national security stories out of the papers.

Cameron told lawmakers Monday that his government is trying to talk to media outlets about "how damaging some of these things can be." But he said that if the outlets "don't demonstrate some social responsibility it would be very difficult for government to stand back and not to act."