WARSAW, Oct 16 (Reuters) - U.S. company Invenergy LLC, which says it has spent more than $600 million building windfarms in Poland, said on Monday it had written Poland's president to say it was formally in dispute with the government over state companies failing to honour contracts.
The company said the letter to Poland's president and prime minister would serve as formal notification of dispute under the U.S.-Poland bilateral investment treaty and the Energy Charter Treaty.
"Bilateral investment treaties protect investors whose rights have been violated by another country, and that is what has happened to Invenergy in Poland," lawyer Michael Blazer said in a statement from the company.
If no settlement is reached within six months it will submit the dispute to international arbitration, Invenergy said.
The offices of the president and prime minister were not available for immediate comment.
Invenergy said it has invested in 11 wind farms in Poland since 2005 and in 2010 signed fixed-price, long-term energy deals with state-run utilities.
But under the pro-coal Law and Justice (PiS) government which took office in 2015, state-run energy companies including Tauron and Energa have scrapped the contracts or deemed them invalid.
To help meet its renewable energy targets coal-reliant Poland has attracted windfarm investors with a subsidies system based on so-called green certificates, securities issued to eligible power generators for each megawatt hour of output.
But the value of these certificates has slumped and the PiS government has looked to curb renewable energy which it says poses a threat to the coal industry.
$1 = 3.5980 zlotys Reporting by Agnieszka Barteczko; editing by Jason Neely