* First quarter gas sales down 2 percent y/y
* Domestic gas production flat y/y
(Adds details, background, shares)
WARSAW, April 18 (Reuters) - Poland's gas monopoly PGNiG natural gas sales dropped 2 percent to 4.8 billion cubic metres (bcm) in the first quarter, the group said in a statement on Monday.
PGNiG added that higher-margin domestic production totalled 1.1 bcm in the period, flat on last year, while remaining sales came from gas imports and storage.
Poland uses around 14 bcm of gas annually with two-thirds imported from Russia and around one-third from domestic gas extraction.
PGNiG sells imported gas at low margins as the price is set by the state regulator. It sometimes sells at a loss, as import prices are based on historic oil prices and the zloty's performance on foreign exchange markets.
The monoply is scheduled to release first-quarter results on May 12. Last year first-quarter revenues reached 6.6 billion zlotys ($2.4 billion) and net profit surged to 988 million zlotys.
PGNiG shares were up 0.8 percent at 3.79 zlotys on Monday, outperforming Warsaw's main index WIG20 which was down 0.3 percent. So far this year PGNiG shares have risen 6.2 percent. (Reporting by Patryk Wasilewski, Editing by Mark Potter)