French President Francois Hollande on Monday urged a quick restart of talks to save Greece from financial disaster after negotiations in Brussels collapsed at the weekend.

"We now have extremely tight deadlines. We are getting into a period which could be turbulent if no agreement is found. This message is for Greece. It should not wait and should restart discussions with the institutions," Hollande told reporters.

"Let's not waste time. Let's restart talks as quickly as possible," Hollande added as he visited the Paris Air Show at Le Bourget outside Paris.

Last-ditch talks between the Greek government and its international creditors in Brussels collapsed over the weekend, raising fears that Athens is moving closer to default and could be forced out of the euro.

The collapse of talks hit the Greek stock exchange hard -— down more than 7 percent in opening trading. The euro was also down on the foreign exchange markets.

Leftist Prime Minister Alexis Tspiras, who was elected on a platform of rejecting austerity imposed by Greece's creditors, said that his government would "wait patiently" until it gets a more realistic offer from its creditors.

The talks in Brussels aimed to break a five-month standoff between the Greek government and its creditor overseers, who are demanding reforms in return for the last 7.2 billion euros ($8.1 billion) of Greece's 240-billion-euro bailout.

The bailout expires on June 30, and to meet that deadline, a reform deal must be resolved by a meeting of the eurozone's 19 finance ministers in Luxembourg on Thursday.