People who use Twitter to breach privacy injunctions may face legal action, according to the government's senior law officer.
Attorney General Dominic Grieve said that individuals could be prosecuted for contempt of court for publishing sensitive material.
Enforcement was normally a matter for whoever had taken out a privacy order.
But Mr Grieve told the BBC he would take action himself if he thought it necessary to uphold the rule of law.
In an interview with Radio 4's Law in Action programme, the attorney general said that individuals who used Twitter or other internet sites to undermine the rule of law could face the consequences of their actions.
He was referring to court powers to fine or even imprison people who deliberately break court rulings.
Mr Grieve explained that enforcement of orders made in civil cases was normally a matter for whoever had taken them out. A claimant could go to court and seek to have people punished if they had broken the terms of an injunction.
But when asked if he should bring contempt proceedings himself for breach of a privacy order, Mr Grieve said he would take action if he thought it necessary.
It was not something he wanted to do, he added.
But the attorney general made it clear that proceedings could be brought against individual Twitter-users in England and Wales as well as against newspapers that dropped heavy hints about the identity of a person protected by an injunction.
In the Commons two weeks ago, Mr Grieve warned people who thought they could use modern methods of communication to "act with impunity" that they might well find themselves in for "a rude shock".
'Civil and criminal liability'
His warning was overshadowed by a question a few moments later from John Hemming MP, in which the Liberal Democrat MP identified Ryan Giggs as the footballer who had taken out an injunction to block reports of an alleged relationship with Imogen Thomas, a reality TV contestant.
Mr Grieve's latest comments go further in his warning to Twitter users that he may himself take action against those who breach injunctions.
And the attorney general's comments were endorsed by David Allen Green, a media lawyer and expert on social media.
"With the rise of the internet everybody's a publisher," he said.
"The law treats self-publication in the same way [as publication by the mainstream media]. It means that a whole lot of people are exposed to civil and criminal liability who wouldn't have been ten years ago."
Like the attorney general, Mr Green acknowledged the unreality of taking legal action if thousands of people broke a court order, especially if they were based outside England and Wales. But these people were running a risk, he said.
Tweeters could not expect Twitter to act in a "libertarian" way and protect them from the courts, the lawyer added. Twitter was a corporation like any other and would have to comply with orders from local courts requiring personal information to be disclosed.
Last month South Tyneside Council said it had gone to court in the US to force Twitter to release the identity of a Twitter user behind allegedly libellous statements about three of its councillors and an official.