Greece has made an "enormous" reform effort since its debt crisis broke out and its international lenders must now grant the country debt relief, OECD chief Angel Gurria said on Monday.

Gurria, who met Greek Prime Minister Alexis Tsipras in Athens, urged Greece to continue with reforms after its third international bailout expires in August.

"I want to congratulate the entire Greek people for an enormous reform effort, it was a very ambitious reform package," he said in translated comments. "And these reforms are bearing fruit."

In its latest survey on Greece, the Organisation for Economic Cooperation and Development sees the Greek economy growing by 2 per cent this year and possibly by 2.3 per cent next year, Gurria said.

He welcomed the country's national growth strategy, which was presented to eurozone finance minister last week, but warned that high unemployment and low investment were still among the challenges that Greece faced.

Tsipras said Greece and the OECD would work together in the post-bailout period and reiterated that Greece does not need any more belt-tightening but relief measures instead.