OPAP, together with gaming technology partners Intralot, Lottomatica and Scientific Games, was the sole bidder for a 12-year licence to run lotteries which generated about 60 million euros (us$ 78 million) of profits last year.
OPAP will take over the state lotteries in a 190 million euro deal, the cash-strapped government's second privatisation this year.
"Lottomatica will exercise its withdrawal right and will give its 33 percent stake in the consortium to OPAP," the source said, adding that the 190 million-euro offer exceeded the terms of Lottomatica's investment.
Lottomatica was ready to back an offer of up to 150 million euros, according to market speculation.