UPDATE 1-PGNiG expects Q2 net results to surpass Q1-CEO

* Imported gas prices decline in Q2 vs Q1

* Still not receiving all contracted Russian gas

WARSAW, May 27 (Reuters) - PGNiG PGNI.WA, Poland's dominant gas provider, expects second-quarter net earnings to improve on the 399 million zlotys ($126.5 million) loss in the first three months thanks to a drop in import prices but complained about a continued shortfall in Russian supplies.

PGNiG, which imports about two thirds of its gas, has been consistently losing money on the Russian gas it sells locally because the Polish regulator has capped its retail prices.

By 1053 GMT, PGNiG shares rose 2.1 percent on Wednesday to 3.90 zlotys, slightly outperforming Warsaw's main WIG20 .WIG20 index.

CEO Michal Szubski told reporters on Wednesday that PGNiG was still not receiving all of the contracted gas from Russia -- an aftermath of the January gas row between Ukraine and Russia -- despite striking a short-term deal with Gazprom (GAZP.MM).

Earlier in May, PGNiG said it reached an agreement with Gazprom Export, an arm of Russian gas giant, to import 1.02 billion cubic metres of gas for $300 million through September. (Reporting by Filip Kochan, writing by Patryk Wasilewski; Editing by David Cowell)