"They are expected to pursue the cases against Greece and the Netherlands for restrictions in sports betting services, barring any last-minute change of mind," the source said.

The action is expected to be in the form of a final warning before the possibility of taking the two countries to the European Union's top court, the European Court of Justice.

EU Internal Market Commissioner Charlie McCreevy is overseeing legal action against 10 of the EU's 27 member states to crack down on national hurdles to competition from gaming firms based elsewhere in the bloc.

Greek gaming company OPAP is an effective monopoly in its home market but competes with other operators in Cyprus.

OPAP shares were trading softer mid-session on Monday, down 0.92 percent at 23.6 euros and underperforming the broader market , which was up 1 percent. "This is not really an immediate problem for OPAP," said an Athens-based analyst who declined to be named. "Greece has said it is arguing for OPAP to be exempt from competition, and it will take a couple of years for a final decision to be taken by the EU in any case."

A spokesman for McCreevy confirmed only that the Commission would discuss legal action at its meeting on Wednesday, with any decisions made public on Thursday.

The ECJ has ruled that EU states can restrict gaming but only in a proportionate and non-discriminatory way.