France and Germany have called a critical meeting for Wednesday with Greece and top European financial institutions, ahead of the summit of the Group of 20 world's biggest and emerging economies.  Protests began Tuesday near the French resort of city of Cannes, site of this week's summit.

French President Nicolas Sarkozy, whose country heads the G20 this year, announced the emergency meeting, following the Greek government's decision to hold a referendum on the European Union debt-relief agreement for Athens.  The Greek move has sent stock markets tumbling and the Europeans scrambling for a way forward.

But President Sarkozy says the EU deal adopted last month is the only option.  Mr. Sarkozy says that giving a voice to the Greek people through a referendum is always legitimate, but that the solidarity of all the eurozone countries can happen only if each state takes the necessary steps.  He says the G20 meeting will focus on the Greek debt crisis.

Protests have already begun ahead of the summit in the Riviera resort of Cannes.  Thousands of people demonstrated in nearby Nice, calling for what they termed "social justice."  Their demands include a tax on financial transactions, more money for economic development and the elimination of tax havens.

Franck Gaye, a spokesman for the protesters, says the demonstrators are coming from across Europe. He says the protesters are very motivated. Gaye says the G20 leaders are obeying financial demands, but that the people want to be heard.

Security is tight in Cannes, with thousands of police mobilized for the summit.