Prime Minister David Cameron has called on the institutions of the eurozone, such as the European Central Bank, to use "everything they have got" to defend the single currency and resolve the current crisis.
Speaking after talks with French president Nicolas Sarkozy in Paris, Mr Cameron said that a "big bazooka approach" was needed to convince the markets that the eurozone institutions have the firepower to put a halt to speculation over the future of their currency.
The Prime Minister also called for "fundamental" reform to address the lack of competitiveness of some EU economies.
He denied that the UK was being sidelined, amid reports that France and Germany are set to agree a joint drive for limited treaty change when Mr Sarkozy meets Chancellor Angela Merkel on Monday, ahead of a crunch summit of EU leaders next week.
Asked if Britain has some influence on the outcome of next week's talks, Mr Cameron said: "Yes it does. We are one of Europe's major economies, we are a big player in the single market.
"We want growth on the European continent to help the British economy. We want to drive change in the single market to get that and we want to help resolve the crisis in the eurozone.
"In the end, what that is about is convincing the markets that the institutions of the euro will defend and protect and promote that currency with everything they have got - the so-called big bazooka approach that I have spoken about.
"But it also means fundamentally grappling with the lack of competitiveness of some European economies and getting to grips with that agenda to make sure that the eurozone can function properly."
Mr Cameron said the reforms to the eurozone to be discussed at the European Council meeting in Brussels on Thursday and Friday of next week would not necessarily require changes to the treaties governing the EU.
But he added: "I am very clear that if there is treaty change then I will make sure we further protect and enhance Britain's interests. We will see what happens next Friday, but the bottom line for me is always what is in the interest of the UK and how can I promote and defend that."
