Group DF companies that own gas in Ukrtransgaz's underground storage facilities will file a lawsuit against the September 29 Cabinet resolution prohibiting mineral fertilizer producers from using gas from underground storage or domestic production until the end of the current heating season.

"Our enterprises that are the owners of gas in storage are filing suit against the Cabinet decision," Group DF Managing Director Borys Krasniansky told journalists.

Group DF companies own about 4 billion cubic meters (bcm) of gas in underground storage. The government did not consult with the group before approving the ban on withdrawals.

The lawsuit will be filed before the end of the week.

Krasniansky said Group DF has a good chance of winning, since the government decision "is absolutely illegal and infringes private ownership."

Despite the ban, Group DF production operations continue at two fertilizer enterprises: Azot (Cherkasy) and Rivneazot.

Prime Minister Arseniy Yatseniuk reaffirmed on Wednesday that the government would temporarily block chemical enterprises from tapping gas inventories currently in underground storage and from buying gas produced at fields in Ukraine, but is ready to provide for transportation of imported gas.

The Ostchem company manages the six fertilizer assets in Dmytro Firtash's Group DF, four of which are located in Ukraine: Stirol, Severodonetsk Azot, Cherkasy Azot and Rivneazot. The former two had to halt operations owing to the fighting in eastern Ukraine and have yet to be restarted.