"(The government) is pursuing a suspicious, non-transparent policy which will lead to the... privatization of the company," the socialist PASOK party said in tabling a question to the prime minister.
PPC has been seeking foreign partners to help it expand operations in Greece and the Balkans, aiming to offset a drop in market share and profit since the country liberalized its energy market last year under EU guidelines.
In December PPC said it was talking with RWE, focusing on a possible joint construction of coal-powered electricity plants, the purchase of wind turbines and cooperation in natural gas and renewable energy.
PPC's board was forced to stop a meeting to discuss a memorandum of understanding with RWE after unions blockaded company offices to protest at what they said is the first step in privatizing the former state monopoly.
"PPC will announce when it will meet to discuss the (RWE) memoranda when it sets the date," PPC said in a filing to the Athens bourse.
Unions have held strikes to protest against any potential deal and have said they will follow up with further 24-hour strikes.
PPC is seeking partners to help it make electricity production more efficient and greener by reducing the amount of lignite it uses to power its plants.
Unions, however, opposes the idea because lignite use allows PPC to keep electricity prices for consumers the lowest in the EU, and because it would involve job cuts.