By Ian Dunt and Alex Stevenson
The government has abandoned its neutral stance on Rupert Murdoch's takeover bid against BSkyB.
Ministers will back a Labour motion saying "it is in the public interest" for News Corporation to withdraw its bid for the broadcaster. The motion will be debated tomorrow in the Commons.
Culture secretary Jeremy Hunt, who has quasi-judicial powers over the takeover bid, will not vote on the issue, the prime minister's spokesman made clear.
"There are times when the House of Commons has got to rise to the occasion and speak for the public," Labour leader Ed Miliband said.
"I am calling on parliament to show its will tomorrow."
The wording of the motion was designed to maximise cross-party support and Lib Dem MPs are expected to support it.
The vote will have no legal or constitutional effect on the deal, but if passed - as now seems highly likely - it would pile on even more political pressure on the Murdoch empire.
Parliament opened up a series of skirmishes with Mr Murdoch today, as the phone-hacking scandal placed the media mogul firmly in the political spotlight.
MPs on the culture, media and sport committee issued an invitation to Rupert and James Murdoch and Rebekah Brooks to answer questions next Tuesday on phone-hacking.
MPs have the power to summon UK citizens if they refuse to appear, although parliamentary history is littered with examples of people who have put off attending hearings to little consequence.
News International said it will "cooperate" with the committee.
"We have been made aware of the request from the committee to interview senior executives and will co-operate," a company spokesperson said.
"We await the formal invitation."
Media reports suggested the request would be met with positively, setting up the possibility of a historic clash between politicians and Mr Murdoch himself next week.
The company has not clarified whether the statement relates precisely to the three individuals mentioned in the invitation, however.
Mr Miliband will meet with deputy prime minister Nick Clegg and Mr Cameron tonight for a meeting which will see them sketch out the shape of the inquiries which have been promised in the wake of the crisis.
Reports suggest that Mr Miliband wants the judge-led inquiry to address general malpractice across multiple outlets - not just the police's relationship with the News of the World and phone-hacking at the newspaper.
The Metropolitan police's involvement in the scandal was the focus of MPs' attentions on the committee corridor earlier, as members of the home affairs committee grilled senior Scotland Yard figures over their attitude to their previous phone-hacking investigations.
Former prime minister Gordon Brown was the latest figure in the public eye to make allegations against News International this morning, when he suggested its journalists had used improper means to find out about his son's medical condition.