Cross-party talks on the best way to implement Lord Leveson's press reform proposals have broken down as an agreement between the three main parties is "too great" to bridge.

MPs will now vote on whether to impose Prime Minister's David Cameron's plans for a royal charter-backed panel to oversee press regulation. They will vote on 18 March.

Deputy prime minister Nick Clegg and Labour leader Ed Miliband have been pushing for legislation to back up regulation, which was recommended by Leveson in his 2,000-page inquiry into press standards following the phone-hacking scandal.

But Cameron told his party counterparts that he was not prepared to regulate the press in law.

The recommendations in the Leveson report were largely rejected by Cameron. He instead proposed a "recognition panel" underpinned by a royal charter, not legislation, to oversee a new press regulator in February.

Cameron described the proposals as "the toughest press regulation this country has ever seen".

After saying that talks between the three main parties had "concluded without agreement", Cameron said the royal charter offered a proven way of regulating the press. There were "real dangers" in writing elements of press regulation into the law, he warned.

Cameron said of Labour and the Liub Dems: "They can back my amendments and support this royal charter to secure a workable system or they can grandstand and end up with a system that I believe will not work.

"What I can't do with effectively a hung parliament is just stand back and say 'we'll negotiate for ever'. We need to bring this to a head, make a decision and put in place something that will work and work quickly."

£1m fines

Cameron added that his proposals would bring upfront apologies, fines of up to £1m and a faster way of dealing with complaints.

He added: "There are real dangers in passing detailed legislation about press regulation.

"It crosses the Rubicon in terms of endangering press freedoms. That is why we propose the royal charter approach. It is a proven way of establishing a public body without the need for legislation, as we've seen with our universities and the BBC.

"The self-regulation must be voluntary.

"There's no point producing a system the press won't take part in."

Press reform campaigners Hacked Off described the royal charter proposals as proof that Cameron was "still protecting his friends in the press and betraying press abuse victims".

Hacked Off's executive director Brian Cathcart, added: This is a shameless betrayal of the victims of press abuse.

It also raises two fingers to all those members of the public who wanted to see change after the Milly Dowler phone-hacking revelations two years ago.

The Prime Minister has walked away from talks in which other parties were trying desperately to accommodate his views on a Royal Charter.

Instead he has chosen to throw his lot in with powerful national newspaper groups, whose actions were condemned in the Leveson Report. His version of the Royal Charter would have paved the way for a regulatory system little different from the discredited Press Complaints Commission.

Cameron is trying to portray this as an issue of press freedom. No serious person believes that the Leveson recommendations on press regulation pose any threat to freedom of expression.

A senior Lib Dem source said: "We thought we were making real progress and inching towards a deal but the prime minister has unilaterally decided to pull the plug on cross-party talks.

"We are still prepared to work with politicians of all parties, including the Conservatives, who want to work with others to implement Leveson."

A senior Labour source said: "The prime minister's decision is very disappointing.

"We still hope for an agreement. We still believe there can be an agreement. We urge the prime minister to reflect on his actions."