Company has invested more than $10 billion overseas so far, with gross value of assets reaching $40 billion

State Grid Corp of China has signed a deal to purchase a minority stake in Greece's power grid operator ADMIE, a move to further extend its international reach.

The company will purchase a 24 percent state in ADMIE, Greece's state-backed Public Power Corporation's subsidiary, for 320 million euros ($349 million), according to the world's largest utility company.