The government has also ordered the Justice Ministry and the management of the state property management agency, which manages the state's stake in MOL, to examine the steps in civil and criminal law that could be taken about the accusations against Hungary and MOL in the MOL-INA case, said MTI.

The Hungarian government has also cancelled Foreign Minister Janos Martonyi's participation at the Croatia Forum on energy security in Dubrovnik on Thursday and Friday, MTI said.

The constant political campaign against MOL in Croatia, Croatian Finance Minister Slavko Linic's threats against the biggest investor in the country and the actions by the Croatian judicial authorities against some MOL executives indicate that they are using means outside the economic sphere to exert pressure, the government's public relations office said.

Those methods are unacceptable in the EU. Hungary cannot allow it and must react, it added.

The Hungarian government's response comes after the Croatian authorities issued an Interpol Red Notice and a European Arrest Warrant for MOL's CEO Zsolt Hernadi after the Hungarian authorities would not serve him with a summons to be questioned in Croatia.

The Croatian authorities suspect Hernadi of bribing former Croatian Prime Minister Ivo Sanader with EUR 10 million into giving MOL management rights in INA.

MOL's stake in INA is a 49.1 per cent, while the Croatian government holds 44.84 per cent.