Greece invited Chinese firms on Monday to bid in a Greek tender for deep-sea oil and gas exploration later this year after Athens extended the bidding process in March.

Greece, which depends on financial aid from the European Union and the International Monetary Fund to stay afloat, has made several fruitless attempts over the past 50 years to find big oil and gas reserves. The debt crisis then prompted the country to step up these efforts to boost revenue.

The new left-wing government of Alexis Tsipras has given investors two more months until July 14 to submit their bids for test drilling on 20 offshore blocks in the Ionian Sea and off southern Crete in a bid to sound out more potential suitors.

Energy Minister Panagiotis Lafazanis and Chinese ambassador to Greece Xiali Zou discussed the issue on Tuesday, the Greek Energy Ministry said in statement.

The envoy committed to informing Chinese oil firms about the Greek tender and the two sides agreed to organise visits by Chinese businessmen to Athens to discuss technical details of the process, the ministry said.

It was not immediately clear which companies might be informed about the tender. No more details were immediately available.

After a visit to Moscow in March, Lafazanis, who represents the far-left flank of the Syriza-led government of Alexis Tsipras, said that big Russian firms were expected to take part in the tender.

The first drilling licences for three onshore and offshore blocks in western Greece were awarded last year. Greece's Hellenic Petroleum - in a venture with Italy's Edison and Ireland's Petroceltic - and Energean Oil & Gas were the winners.

Hellenic and Greece's sole oil producer Energean, 45 percent owned by hedge fund Third Point, were the only two firms which bid for another three onshore blocks in western Greece in February.

Greece has been locked in talks with its EU/IMF creditors for months and risks running out of cash soon. The country has been looking elsewhere, including Russia and China, to attract investors and boost its depleted coffers.