Donald Tusk says it's up to Greece to decide whether it wants to leave the single currency, or take what he says is a 'good offer' of financial support.

President Tusk has called a meeting on Monday to discuss the crisis, and decide if Greece should be given more loans to avoid default.

He says the time for action is now.

The Kremlin says there's been no discussion of financial aid for Greece at a meeting between the Russian President and Greek Prime Minister.

A Russian official was quoted as saying Moscow would consider helping.

Meanwhile, the European Central Bank has agreed to increase emergency credit for Greece's banks.