The Latest: Greece's Varoufakis will quit if 'Yes' wins

Greek Finance Minister Yanis Varoufakis has said he will resign if there is a "Yes" vote in Sunday's referendum over recent creditor proposals.

Credit ratings agency Standard & Poor's is warning that a "distressed" Greek exit from the euro would have "severe" consequences for the country's economy.

It adds that Greece would permanently lose access to financing from the European Central Bank, which would create a serious foreign currency shortage for the private and public sectors.

Sapin had been pushing for an agreement with Greece before Sunday's referendum, but after a fruitless meeting of European finance ministers Wednesday, he conceded that there's no point negotiating until after the vote.

European stock markets have opened steady, a day after Greece's European creditors said they would not talk with the Greek government about its bailout request until after Sunday's referendum.

"The Greek government would appear to continuing its game of cat and mouse with its creditors," said Michael Hewson, chief market analyst at CMC Markets.