Greece must realize there is no other way than to reform, European Central Bank governing council member Luc Coene said in an interview published on Saturday, telling Greeks they had been sold "false promises" by radical leftists now in power.

The Belgian central bank chief said that life outside the euro zone would be far worse for Greek people and warned that if Athens wanted to be financed by the euro zone, the ECB and the International Monetary Fund, it had to follow the rules.

"I do not believe there is a radically different way," he told Belgian daily De Tijd. "Syriza has made promises it can not keep," he said, adding that the Greek people "will understand quickly that they were deceived by false promises."

Like his euro zone colleagues, Coene had a clear message for Greece, saying: "Reform is the only way ... Tell me where the money should come if the Greeks do not want reform and do not want to repay other European countries?"

Greeks voted for Alexis Tsipras, leader of Greece's far-left Syriza party, in January because of his promises to renegotiate the country's EU/IMF bailout that many feel punished the country and drove it into an economic depression.

But EU leaders say Greece's prospects have improved greatly since it nearly crashed out of the euro in 2010 and, as economic growth returns, urge it to continue the reform process.

Still cut off from financial markets, Tsipras eventually requested a four-month extension to its euro zone bailout last month. Athens needs to deliver detailed plans to get new loans.

"If they leave the euro, it will be ten times worse for them. Ten times," Coene said.

Euro zone finance ministers will discuss Greece's reforms at their meeting in Brussels on Monday, but time is short, because Greece is facing big repayments to its creditors and is running out of cash to fund itself.