ATHENS, Aug 5 (Reuters) - Hellenic Exchanges, the operator of Greece's stock and equity derivatives markets, said on Thursday it will buy a 10.24% stake in the Belgrade Stock Exchange (BELEX), joining forces to strengthen their presence in Southeast Europe.

Hellenic Exchanges said it had been given the green light by Serbia's securities regulator for the acquisition. It did not say how much it will pay for the stake in BELEX.

As part of the deal, BELEX will migrate trading to the Athens stock exchange's trading platform, Hellenic Exchanges said.

Market participants will benefit from the enlargement of both capital markets and the cross-trading opportunities offered, the Greek bourse operator said.

"Hellenic Exchanges, both as a market operator and as a public company has the necessary experience to support BELEX to grow its capital market through this strategic alliance," Socrates Lazaridis, CEO of Hellenic Exchanges said.

AXIA Ventures Group Limited advised Hellenic Exchanges on the transaction.

With BELEX, the Cyprus stock exchange and the Greek bourse on a common trading platform, Hellenic Exchanges is taking another step towards its long-term goal for sustainable business, increasing theliquidity pool and broadening its regional network, Lazaridis said. (Reporting by George Georgiopoulos; Editing by Kirsten Donovan)