PPC, which is 51 percent state-owned, has struggled to shore up its finances after it was forced to make provisions for overdue bills left unpaid in austerity-hit Greece in recent years. Lower market share along with higher wholesale electricity prices and carbon emission costs have also weighed down on profit.

PPC has reported a higher net loss for the nine-months.

"Al these are putting pressure on PPC's results, (they are causing) a decline in profit," Chief Executive Officer Manolis Panagiotakis told a parliamentary committee on Wednesday.

"If this doesn't stop, it will be harder for us to tap the markets, which is our main aim."

But Panagiotakis said he was confident that PPC will repay bank loans of about 250 million euros (218 million pounds) and a 350 million euro bond due in May.

In an effort to boost profits, PPC had considered raising its rates. However, the government has ruled it out.

(Reporting by Angeliki Koutantou, editing by Louise Heavens)