Piers Morgan has told Hugh Grant to quit his newspaper crusade in the wake of the Leveson inquiry and "go back to your dreadful movies".
The CNN host and former Mirror editor aimed the tweet at the Love Actually star, who had been bemoaning the lack of progress in implementing the recommendations of Lord Justice Leveson's report.
Morgan also branded Grant and Alan Partridge star Steve Coogan, also at the forefront of the Hacked Off campaign, "guttersnipes".
It came as David Cameron, Nick Clegg and Ed Miliband met to try to reach agreement over the best way forward for reforming the press.
Labour upped the pressure on the Tories by tabling amendments that would leave it the option of inserting tough statute-backed reform into the Crime and Courts Bill on Monday.
The move effectively sets a deadline for Mr Cameron to either make progress on the issue or face a Commons vote - which he could lose as Labour and the Lib Dems join forces with some Tory backbenchers.
Speaking on the BBC's World At One, Grant said Cameron had "lamentably betrayed" a promise given to the relatives of Madeleine McCann and Milly Dowler, that he would implement Leveson unless it was "bonkers".
Even the Tories' preferred option of a Royal Charter instead of statute had been watered down, he claimed.
He said: "For the last three months, newspapers have applied so much pressure to the government that the Royal Charter has been watered down to something that's pretty much meaningless."
"This will keep happening and the Government's legislative agenda will be completely screwed because no one will give up on this," he said of the move to open the Crime and Courts Bill option.
He also told the Daily Politics show: "This is the will of the people and it is not right that a tiny rump of Conservatives who happen to be in the executive are doing the will of the press, who they desperately need to stay there because the rest of their policies have gone cock-eyed."