Under a privatisation scheme agreed in the terms of its bailouts, Greece should have launched the sale of its 65-percent stake in DEPA earlier this year.
The government last month presented an alternative proposal that involved splitting DEPA into two entities, one covering its wholesale and retail gas supply business and the other its distribution network and international activities.
Greece agreed on Monday to sell a 50.1 percent stake in DEPA's wholesale and retail gas supply operations, Energy Minister George Stathakis told Greek state television ERT.
The sale process would conclude in the first quarter of next year, and the other part of DEPA would remain under state control, he added.
There was no immediate comment or confirmation from the creditors.
Greece's third international bailout expires in August. But Athens will need more time to conclude agreed privatisations, including stake sales in oil refinery Hellenic Petroleum , in power utility Public Power Corp. (PPC), in Athens' main airport and in water utilities.
Since its first bailout in 2010, the country has raised about 5 billion euros from privatisations and is aiming at another 3 billion euros by 2019.