The leaders of the 16 eurozone nations have agreed to measures to protect the value of the single European currency and approved $145 billion in emergency loans to Greece.
French President Nicolas Sarkozy said Saturday in an emergency meeting in Brussels that it is vital that Europe create a plan to defend itself from aggressive market movements.
At Saturday's meeting, European leaders acknowledged that the eurozone's problems could spread beyond debt-ridden Greece to other troubled countries such as Spain and Portugal.
Finance ministers of all 27 European countries are to hold talks on Sunday in Brussels to adopt special measures designed to calm financial markets rattled by the Greek debt crisis in advance of Monday's market openings.
As the leaders gathered in the Belgian capital, German Chancellor Angela Merkel called on eurozone members to tighten their budgets and increase regulation of financial markets. She warned that bailing out Greece will not be enough to prevent further financial turmoil, both in Europe and elsewhere.
U.S. President Barack Obama spoke by telephone with the German leader on Friday and voiced support for current efforts to rescue Greece.
Some financial experts have expressed concern that the Greek bailout may be coming too late.
This week saw violent protests in Greece over austerity measures adopted by the government of Prime Minister George Papandreou that include spending cuts and tax increases.
Some information for this report was provided by AFP and AP.