ATHENS, June 23 (Reuters) - Public Power Corp. (PPC) , Greece's biggest utility, is close to a deal to sell a bundle of unpaid bills worth about 300 million euros ($339 million) to JPMorgan, two sources close to the matter said on Tuesday.

PPC, which is 51% state-owned, is struggling under a pile of about 2.7 billion euros of electricity bills left unpaid from Greeks hard up because of the country's decade-long debt crisis.

The utility has been working for months on a plan to securitise part of the arrears and sell them to investors.

It will now seek to raise 200-250 million euros from the transaction which includes arrears of up to 60 days, one of the sources said, adding that the deal will be discussed at a board meeting on Tuesday.

The utility declined to comment.

PPC is also looking to securitise and sell a second tranche of bills in arrears for more than 90 days which are considered non-performing, the second source said.

The sources said that the second transaction is expected to conclude in either September or October.

PPC has mainly used lignite, or brown coal, which emits a large amount of carbon, to produce energy.

Under new management which took over last year it plans to switch off all but one of its coal-fired plants by 2023.

It also plans to boost investment in renewables to help Greece align with the European Union's goal of achieving net zero carbon emissions by 2050.

(1 = 0.8861 euros) (Reporting by Angeliki Koutantou; editing by Jason Neely)