A further row over Britain's membership of the European Union broke out this evening after David Cameron suggested there could be scope for current treaties to be renegotiated.

This afternoon at a press conference following a meeting of European Union leaders, the Prime Minister said that the talks had referred to "the possibility of treaty change: that will be looked into and reported back at the December summit". But he warned that treaty change would only happen if all member states agreed to it. "Any treaty change, as the last treaty change did, is an opportunity for Britain to advance our national interest," he said.

The Prime Minister's words may have come as a comfort to MPs within his own party who plan to defy their party whip tomorrow and support a motion calling for a nationwide referendum on whether Britain should stay in the EU. But they sparked tensions with his Liberal Democrat colleagues, with a spokesman for Nick Clegg saying: "It is far too early to speculate on the Government's negotiating position in a future inter-governmental conference which may well not happen and to which many countries would object."

Labour leader Ed Miliband also accused Mr Cameron of bringing the split within his party over Europe upon himself.

Mr Miliband told the Politics Show that David Cameron had "brought's tomorrow's events upon himself". He added that the Prime Minister has appeased his party's eurosceptics and left himself in a difficult position ahead of tomorrow's debate, which calls for a nationwide referendum on whether Britain should leave the EU, renegotiate its treaty with Brussels, or remain a member on current terms.

A number of high-profile Conservatives today defended the three-line whip placed on Conservative backbenchers to vote down the motion. New Defence Secretary Philip Hammond told the Andrew Marr Show: "The three line whip remains because the motion is contrary to Government policy."

He was joined by International Development Secretary Andrew Mitchell, who told the Politics Show that holding a referendum on the EU would be "just a distraction".

Former Conservative leader Michael Howard also backed the position, telling Murnaghan on Sky News that an EU referendum would be a mistake in current conditions.

But prominent backbenchers, including Mark Pritchard, Bernard Jenkin, Priti Patel and John Redwood continue to oppose the three-line whip. Mr Redwood said he "would now ask that we have a free vote", while Mr Pritchard warned that "any wounds endured over this debate, and over the coming months, will be very much self-inflicted". Mr Jenkin also warned that the Conservative party could become "irrelevant in the eyes of voters" if the three-line whip is pursued tomorrow.

The Liberal Democrats have similarly been instructed to reject the motion. The party's deputy leader Simon Hughes said a referendum would be a "complete distraction" from the eurozone and UK economic problems.