IMF chief Christine Lagarde has warned of a risk of "contamination" if Greece quits the euro.
In an Interview with the BBC she said the Eurozone might see the value of paying more to keep Greece in.
She said a Greek exit from the single currency is "certainly not the most favourable option and not one that we encourage".
Her comments come ahead of a summit of EU leaders later.
They are under intense pressure to agree economic growth plans and to deal with the Greek crisis.
Christine Lagarde said a Greek exit is not the most favourable option and not one that the IMF would encourage.