U.S. oil supermajor Chevron Corp. and Polish state-controlled energy company PGNiG will team up to explore for shale gas in the Eastern European country, whose reserves of that "unconventional" fossil fuel are estimated at 800 billion cubic meters.

PGNiG said Friday that the memorandum of understanding it signed with Chevron was the first agreement of its kind between a Polish and foreign company in the shale-gas sector.

"The initiative is in keeping with PGNiG's new policy of greater openness, which should lead to partnerships with other companies interested in gas deposits in Poland," the company said in a statement.

Under the Polish government's plan, U.S. experts will contribute their experience in exploring shale deposits while Polish companies will facilitate access to exploration licenses and good relationships with local authorities.

The focus of the cooperation agreement between Chevron and PGNiG will be on shale deposits in the eastern Polish region of Lublin.

Poland, which imports - mainly from Russia - much of the 15 billion cubic meters of natural gas it consumes annually, could substantially reduce its energy dependence if its shale-gas potential is confirmed.

The Polish government has awarded shale-gas exploration concessions to foreign multinational companies with a view to developing those reserves in the coming years.

Shale gas is extracted using a controversial method known as hydraulic fracturing, or fracking, which involves pumping a pressurized fluid - usually composed of water, sand and chemicals - into low-permeability rocks to create a fracture in the rock layer and release pockets of the trapped fuel.

Fracking opponents in the European Union - led by France, which has banned the technique - have raised alarm bells about its environmental impact. EFE