Greece's gaming monopoly firm OPAP changed hands on Friday, 55 years since its establishment, after a major stake in the company was sold to foreign investors in the biggest privatization program since the start of the country's debt crisis.

The sale of the 33-percent stake of the state lottery and betting agency to Greek-Czech Emma Delta consortium for a sum of 622 million euros (843.7 million USdollars) was completed on Friday, a statement from the Hellenic Republic Asset Development Fund (HRADF) said.

According to the statement, the fund will receive further 30 million euros in 10 equal installments over the next decade, adding that "the deal marks the completion of the biggest privatization since the start of the privatization program."

In another statement issued shortly afterwards, Emma Delta announced the appointment of Czech businessman Jiri Smejc as the new chairman of OPAP. Greek businessman Yorgos Melissanidis, the second key stakeholder in Emma Delta, was appointed as a member of OPAP's new board.

OPAP's gross gaming revenues in 2012 reached 1.3 billion euros. Emma Delta estimates that it will be doubled next year with an upwards trend for the following years, since OPAP will retain the monopoly in sports betting and lotteries for at least a decade.

The deal was initially clinched in May and signed on August 12 by Melissanidis and HRADF's then president Stelios Stavridis.

Stavridis was dismissed a few days after the deal, when it was revealed that on the same day he had gone on vacation on a Greek island on the businessman's private plane.

Earlier this week the Greek parliament approved the appointment of Constantinos Maniatopoulos as new the HRADF chief. The former president of the Greek Public Properties Company, a state company which manages state-owned tourism property, has pledged to step up efforts to meet the goals of the privatization program's targets.

The program, launched in 2010, is a key part of the overall Greek stability and growth plan introduced to address the crisis under bailout deals with international lenders.

Nevertheless, the program has been hit by delays and snags and its targets have been revised downwards several times.