WARSAW (Reuters) - Canada's Talisman Energy (>> Talisman Energy Inc.) may pull out of shale gas operations in Poland, it said on Tuesday, a step that would make it the second big foreign player to withdraw from what had been seen as Europe's most promising source of shale gas.

U.S. major Exxon Mobil (>> Exxon Mobil Corporation) has already decided to drop its Polish shale gas plans after disappointing returns from its test wells.

Talisman did not cite any problems with its Poland operations but some investors have been jolted by the government's downward revision of estimates for the volume of shale gas in Poland, and are concerned about their poor drilling results in difficult geological conditions.

"Talisman Energy is changing its operation strategies for the coming years as the result of changes on the oil and gas market," Tomasz Gryzewski, director at Talisman Energy Poland, told Reuters.

"Divestment options, including in Poland, are being considered. The management will release its decisions together with first-quarter results," he said.

Talisman owns three of 109 shale gas concessions in Poland. Other global players such as Chevron (>> Chevron Corporation) and ConocoPhilips (>> ConocoPhillips) are active in the Polish shale gas sector.

The government is counting on shale gas to help reduce its dependence on oil and gas imported from Russia, and to wean it off greenhouse gas-emitting coal-fired power stations.

(Reporting by Agnieszka Barteczko; editing by Jason Neely)