Warsaw estimates it has as much as 3.3 trillion cubic feet of natural gas, lower than the 187 trillion cubic feet estimated by the U.S. Energy Information Administration.
Officials, however, said shale gas analysis carried out in conjunction with the U.S. Geological Survey confirmed the country remains in position to become a major energy producer and that more drilling will likely reveal greater reserves.
Polish politicians are divided over what role foreign entities should play in the country's shale natural gas sector.
"Politicians don't want to do the wrong thing but they lack experience and this makes it difficult for them to be a partner with a strong industry," Pawel Poprawa, a shale gas expert formerly with the Polish Geological Institute, told the Platts news service.
State-controlled natural gas company PGNiG holds most of the shale concessions in the country among rival energy players.
One official who spoke with Platts on condition of anonymity said there was an emerging climate of xenophobia in Warsaw. Polish Deputy Environment Minister Piotr Wozniak, however, denied the allegations.
"If we really want to develop these resources we need foreign investors," he said.