The country's quest to explore for shale gas began five years ago, when the then prime minister Donald Tusk raised hopes with a forecast of it coming on stream in 2014.
This attracted global energy majors, including Chevron, ExxonMobil and Total, but one by one they pulled back after disappointing results and a slump in oil prices.
Polish state-run firms, including PGNiG and PKN Orlen were the last ones to work on the country's shale gas projects.
"The
