The first reliable estimates of northern Poland-located shale gas deposits will be available in the spring 2011, while for the entire country's resources - at the end of next year, said Jerzy Nawrocki, head of the State Geological Institute (PIG).

PIG has not published yet any assessment of the potential resources but according to some consulting companies, such as Wood Mackenzie and Advanced Resources International these may include 1.4 billion cubic metres of shale gas or 3 billion respectively.

Nawrocki said that PIG is unable to confirm or deny these estimates. Its measurement will be worked out in cooperation with the US Geological Survey.

Poland has awarded more than 70 concessions for unconventional gas explorations to over 40 companies. Around 25 percent of them are held by the domestic gas company Polskie Gornictwo Naftowe i Gazownictwo (PGNiG), while those remaining are held by others, including Lane Energy Poland, BNK Petroleum, San Leon Energy plc., Realm Energy International and Exxon Mobil