David Cameron's hopes for cross-party consensus on a response to the Leveson Inquiry were dashed after Labour leader Ed Miliband insisted that a new press regulator should be established in law.
The Prime Minister said politicians should be wary of legislation which could potentially "impinge free speech and a free press".
But Mr Miliband said without a legal underpinning for any new regulator "there can't be the change we need".
Mr Cameron called for immediate cross-party talks with Mr Miliband and Liberal Democrat leader Nick Clegg, the Deputy Prime Minister.
Mr Clegg sat beside Mr Cameron as he made his statement, but used his own appearance at the despatch box to set out his views on the Leveson Inquiry in a sign of division at the top of the coalition.
In a statement to the Commons Mr Cameron insisted he agreed with the "Leveson principles" on regulation but was not convinced new laws were necessary.
The Prime Minister said the press should be given a "limited period of time" to put a new system in place. "While no one wants to see full statutory regulation, the status quo is not an option," he warned.
Mr Miliband described the Leveson principles as "measured, reasonable and proportionate", and supported the recommendation that a regulator should be backed by law.
"We endorse Lord Justice Leveson's proposal that the criteria any new regulatory body must meet should be set out in statute," said Mr Miliband. "Without that, there can't be the change we need."
He suggested a timetable for implementing the proposals be discussed when party leaders hold talks. Mr Miliband said: "These talks must agree a swift timetable for implementation of these proposals, agree to legislate in the next session of Parliament starting in May 2013, with a new system up and running at the latest by 2015." He also backed a role for Ofcom, saying it would provide a "crucial, new guarantee", and be a "truly independent regulator".