Shropshire MPs this afternoon piled the pressure on David Cameron as the Prime Minister came under renewed pressure on the eve of a crunch EU summit meeting.

Wrekin MP Mark Pritchard urged Mr Cameron to seize powers back from Europe as fears grew that the summit would lead to another European treaty. Cabinet minister Owen Paterson also spoke out about the possibility of a referendum.

Mr Paterson, who represents North Shropshire, suggested a referendum would be an ‘inevitable’ result of proposals for closer fiscal union in the eurozone.

Speaking at Prime Minister’s Questions this afternoon, Mr Pritchard said the Prime Minister had his full support in standing up for Britain’s national interest.

But he added: “Is it not the case that bailout after bailout of the eurozone will not save Europe or the eurozone, but making Europe more competitive, reducing its high unit costs and cutting regulation and red tape on business will?”

Mr Cameron said Germany wanted to see tougher fiscal rules about budget deficits for eurozone members but at the ‘heart of the crisis’ was the differing competitiveness of countries within the single currency.

The Prime Minister also said there was now a referendum lock which meant further powers could not be passed to Brussels without the consent of the public.

Earlier today, Mr Cameron promised he would not sign up to any deal which did not safeguard the UK’s interests. Safeguards he wants include measures to protect Britain’s financial services amid fears the City of London will be hit hard by a possible transaction tax and protections for the single market.

French president Nicolas Sarkozy and German chancellor Angela Merkel renewed calls for reform of the treaty after emergency talks in Paris on Monday.

The aim would be to allow far tougher rules and sanctions governing the eurozone in future to reassure markets about the euro’s long-term stability.

But Owen Paterson, the Northern Ireland Secretary, today said: “If there was a major fundamental change in our relationship, emerging from the creation of a new bloc which would be effectively a new country from which we were excluded, then I think inevitably there would be huge pressure for a referendum.”

Asked whether a referendum will be required, he replied: “I think there will have to be one, yes, because I think the pressure would build up. This isn’t going to happen immediately because these negotiations are going to take some months. But I think down the road that is inevitable.”

A source close to Mr Cameron tried to play down the significance of Mr Paterson’s remarks, telling reporters: “It’s a difficult issue and I think Owen was trying to be helpful.”