But now hopes are running out before Athens has to make big loan repayments in June to the International Monetary Fund (IMF) and European Central Bank (ECB), which holds maturing Greek bonds.
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As crunch time approaches, Greece has yet again been one of the hot topics at a summit of European Union (EU) officials in Riga, Latvia, on Thursday.
On Thursday and Friday, the German and French leaders, Francois Hollande and Angela Merkel, met with Greek Prime Minister Alexis Tsipras on and urged him to work with lenders to find a solution, according to Reuters.
Speaking to reporters at the summit, Merkel said the chat with Tsipras was "a very friendly, constructive exchange, but it's also clear that there must be more work with the three institutions. There is a lot to do."
Buiter agreed that some kind of deal had to be "concocted" in the next few weeks "because it looks likely that Greece is simply going to run out of money sometime in June and won't be able to pay its domestic bills and its foreign creditors."
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However, he believed a default on its debts would "not be the end of the world."
"A default would of course be serious for Greece and it would cause a re-awakening of sovereign fears throughout the periphery of the euro area but it's not the beginning of a Grexit necessarily."
He believed that Greece would stay in the euro zone and should "have serious debt restructuring and serious structural reform in Greece."
"There is a point at which Greece has to become serious about structural reforms," he said.
- By CNBC's Holly Ellyatt, follow her on Twitter @HollyEllyatt. Follow us on Twitter: @CNBCWorld