The Greek government approved on Thursday plans for oil exploration and drilling in western Greece that could raise up to 25 billion euros (33.57 billion U.S. dollars) in revenues in the next two decades.

The project is promoted in the context of efforts to reduce the country's heavy dependency on energy imports and solve a severe Greek debt crisis with the assistance of European Union and International Monetary Fund.

"This is the first time Greece is doing this, and everything will be conducted with full transparency," said Environment, Energy and Climate Change Deputy Minister Yannis Maniatis at the end of a cabinet meeting.

Maniatis announced that the drilling will take place in the Gulf of Patras, the sea region west of Ioannina in Epirus prefecture and Katakolo, off the coast of Peloponnese.

The formal "open door" invitation of interest to investors will be issued in January 2012, he added.

It is estimated that three regions under review could produce as much as 300 million barrels of oil over a period of 15-20 years that could raise some 15 billion euros (20.11 billion U.S. dollars) for the Greek state and 10 billion euros (13.41 billion U.S. dollars) for investors.

It is not the first time Greece decided to allow for drilling in western Greece. In 1997 a similar exploration project ended with no concrete results due to "technical reasons."

This time under an over 350 billion euro (469.32 billion U.S dollars) debt burden that threatens the eurozone member country with default since late 2009, Athens explores all options to reduce budget deficits and raise revenues.

According to Greek officials, procedures for seismic studies for possible hydrocarbon deposits in South Crete on the Aegean Sea will soon be completed.

"Whatever has been said the last 15 years for the oil deposits in Greece will be judged in a few months time. We will know if there are deposits, the exact sites and how much oil we have. But one should not expect that Greece will solve the debt crisis by finding oil", Maniatis said recently.

The basic priorities of the energy policy amidst the crisis is the security of the supply, the reduction of dependence on energy imports and the tackling of climate change and instability in the international energy market, he explained.