Greece's parliament gave the go-ahead on Wednesday for companies including France
's Total and Italy's Edison to explore for oil and gas in the west of the country.
Licences for four blocks - one offshore and three on land - were awarded in 2016 but had to be ratified by parliament for exploration work to begin.
Encouraged by recent large gas finds in the eastern Mediterranean, Greece is eager to attract investment in its energy sector as it tries to emerge from years of economic crisis. Western Greece is an underexplored area and very little data exists on its hydrocarbon potential.
A Total-led consortium with Edison and Greece's biggest oil refiner Hellenic Petroleum was awarded Block 2 in the Ionian Sea; Hellenic Petroleum was also awarded the Arta-Preveza and northwestern Peloponnese onshore blocks and Energean, Greece's only oil producer, the Aitoloakarnania onshore block.
Hellenic Petroleum holds an exploration licence in the Patraikos Gulf off the Peloponnese peninsula and plans the first test drilling there in 2019. Energean also plans to start drilling in another field off the peninsula in 2019.
"We are turning a new page in the chapter of tapping into hydrocarbons," Energy Minister George Stathakis told parliament before the vote.
He said the country was slowly catching up with Cyprus, Israel and Egypt.
Total has shown interest in the eastern Mediterranean following major gas discoveries
off Israel and Egypt. It is currently drilling for oil off Cyprus.
Together with Hellenic Petroleum and U.S. oil major Exxon Mobil (XOM)
, it has also expressed interest in exploration at two sites off Crete, prompting Greece to launch a tender.
The Greek branches of Greenpeace and the World Wildlife Fund (WWF) had called on lawmakers to reject the bills ratifying the contracts, saying iconic and ecologically sensitive marine and coastal areas were at great risk.
The bills "trapped the country in a growth model that is extremely polluting and dangerous to humans and the environment," they said in a statement.
Stathakis said Greece will make sure that strict environmental rules will be applied.
(Reporting by Angeliki Koutantou and Karolina Tagaris, editing by David Evans)