David Cameron has urged fellow EU leaders to take "decisive" action over Greece and agree longer-term plans to beat the wider eurozone crisis.
Arriving for an EU summit over dinner in Brussels the Prime Minister said: "This is an important meeting for Britain because what happens in the eurozone affects our country."
It was time for decisive plans for Greece, to help get the economy moving, he said, adding: "But if we are not to keep coming back and back to meetings like this we also need coherent long term plans - otherwise this crisis will keep re-occurring."
PM urges EU to act over Greece
New French President Francois Hollande arrived for his first EU gathering of leaders since his election insisting on the need for more emphasis on economic growth - setting himself up for a major showdown with German Chancellor Angela Merkel, who says austerity measures must take priority to tackle debt and deficits.
He also pressed the case for establishing eurobonds in the 17-nation eurozone to raise money to take the pressure off indebted countries - anathema to Germany, which would see the cost of its borrowing rise.
The summit opened amid falling markets as speculation rose about eurozone readiness to concede that Greek departure from the single currency may be inevitable. In London the FTSE 100 Index closed 2.5% lower, off 136.9 points at 5266.4.
EU officials say little can be done - or said - by EU leaders to resolve the Greek crisis until a national election re-run due on June 17.
Meanwhile, they said, the focus is on restoring confidence in the European economy through a series of practical measures to inject more growth into the current austerity-based remedies being imposed on Greece in return for massive financial bail-outs.
The only clear agreement at the summit was determination to keep Greece in the eurozone if possible.
But officially Greece was not on the dinner debate menu, where the agenda centres on growth-boosting initiatives, such as targeting more money on major structural projects to generate jobs and revenue and reinforcing the EU's single market for trade.