French President Nicolas Sarkozy will discuss Greece's decision to hold a referendum on its bailout deal with German Chancellor Angela Merkel on Tuesday afternoon and then hold an urgent ministerial meeting, Sarkozy's office said.

Markets tumbled across Europe in response to the announcement of a referendum, which is expected to take place in a few weeks.

Last week's 130 billion-euro ($180 billion) bailout package had raised hopes a line could be drawn under banks' Greek losses and euro zone bonds could be sold to China and other investors.

Sarkozy's office said he would meet his top ministers, including the prime minister, finance minister and foreign minister as well as the central bank governor, at 1700 local time (1600 GMT) to discuss Greece's decision.

No statement is due after the ministerial meeting, a presidential source said.

Share prices of French banks and other lenders exposed to Greece and other weak euro zone countries slumped on Tuesday.

Societe Generale tumbled 13 percent and BNP Paribas and Credit Agricole fell more than 10 percent. They are among the most exposed to Greece through sovereign debt holdings and loans.

We have just added fuel to the fire and we don't understand at all the decision of the Greek PM, said Marc Touati, chief economist at Assya Compagnie Financiere in Paris.

If there is a referendum the 'no' will win. Greece is playing a suicidal game that could lead to its exit of the euro zone so there is fear on French banks, but also on (euro zone) states.

REBUKE

The Greek government's decision brought a sharp rebuke from a former industry minister and close ally of Sarkozy within his UMP ruling party, Christian Estrosi, who called the move totally irresponsible.

When we are in a crisis situation and others want to help you it is insulting to try to save one's skin rather than to face one's responsibilities, said Estrosi.

Far-right leader Marine Le Pen, who is seen winning 10 percent of the vote in next year's presidential elections with calls for more protectionism and for France to leave the euro, said it was time for European leaders to come up with a plan B to prepare an exit from the euro before catastrophe and panic strikes.

We tried to gain time at an exorbitant cost for the people knowing that the end was inevitable, Le Pen told i-Tele television.

We now need to get round the table and prepare a concerted, intelligent plan to leave the euro with our European partners. This mad dash must end otherwise there will be revolt among European people.

(Writing by John Irish; editing by Andrew Roche)

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