Polish state firms agree to spend $511 mln on shale

WARSAW, July 4 (Reuters) - A consortium of several state-controlled Polish companies agreed on Wednesday to spend 1.7 billion zlotys ($510.5 million) on joint exploration and extraction of shale gas, which Poland hopes will help diversify its energy sources.

The group of companies that will work together in three locations is made of Poland's gas monopoly PGNiG, copper miner KGHM and three largest utilities -- PGE , Tauron and Enea. ($1 = 3.3301 Polish zlotys) (Reporting by Maciej Onoszko and Pawel Bernat, writing by Chris Borowski)