Online gambling firm GVC Holdings, which has a presence in the Greek market through a partner, said it had seen a fall in player activity in that territory.
The company said it was too early to forecast whether this would have a material effect on the second half of the financial year for its Greek operations.
GVC's other markets continue to trade well and the board remains confident in year-end expectations, the company said, and declared a quarterly dividend of 14 euro cents.
The company operates through its partner Centric Multimedia SA in Greece, which shut its banks to limit strains on its crippled financial system.
Sports betting is incredibly popular in Greece, where companies like OPAP, Europe's second-biggest gambling firm by market value, provide numerical lottery and sports betting games.
The Isle of Man-based GVC operates in more than 20 countries and is licensed in Malta, Denmark, UK, South Africa, Alderney and the Dutch Caribbean.
GVC, which offered to buy bigger rival Bwin.Party Digital Entertainment Plc, said on Wednesday it was in continued talks with the company.
The Financial Times reported on Tuesday that GVC Holdings has offered about 900 million pounds for Bwin.Party.
Reuters