Earlier this week Prime Minister Jadranka Kosor said the government would decide that no one can acquire more than 49 percent of INA, citing Croatia's strategic interest in the biggest national energy group.

"We decided to wait for the end of an investigation started by the state prosecution office on recent suspicious acquisition of INA shares," Kosor told a cabinet session on Saturday.

INA's biggest shareholder is Hungary's with a 47.25-percent stake, while the government owns 44.84 percent.

Croatia's financial watchdog HANFA on Monday suspended trade in INA on the Zagreb stock exchange while it tries to identify foreign investors who have been buying shares in recent weeks when its price surged to an all-time high of 4,050 kuna ($778.1) despite a relatively small volume that changed hands.

There was a market speculation that an investment fund originating in Cyprus was acquiring shares.

Some local analysts suggested a decision about preventing majority ownership could complicate Croatia's ambition to wrap up the European Union entry talks in the coming months as it might violate an EU rule on the free flow of capital.

Two months ago MOL failed in a public bid to become the majority owner of INA amid a heavy trade by local institutional investors which were supported by the government in acquisition of shares.

Kosor said on Saturday the government would seek to protect the national interest in the energy field, but would also talk to MOL about the best possible solution in doing so.

INA has upstream and downstream activities and is involved in gas and oil exploration in Croatia, Africa and the Middle East, notably Syria.