Ukrainian Prime Minister Arseniy Yatseniuk has accused businessman Dmytro Firtash of the deliberate stoppage of Rivneazot and Cherkasy Azot under his control due to his unwillingness to pay a UAH 6 billion debt for gas to national joint-stock company Naftogaz Ukrainy and has threatened to nationalize these large chemical enterprises.

"These plants were closed due to the simple reason that this organized crime group owes UAH 6 billion to the state. If the companies do not pay for gas to Naftogaz Ukrainy, these companies will be transferred to state ownership, and the state will give jobs in Rivne and Cherkasy," Yatseniuk said in the parliament during question time on Friday.

Group DF uniting assets of Firtash said in late May that the group has halted the operation of Cherkasy Azot and Rivneazot, it says due to pressure being put on the business by People's Front MPs and their representatives.

"Due to systemic and unprecedented pressure on Ostchem's business, the chemical holding of the group, by MPs from People's Front and their representatives in power, Group DF announced the stoppage of operation of Ostchem's enterprises - Cherkasy public joint-stock company Azot and public joint-stock company Rivneazot," the press service of Group DF told Interfax-Ukraine.

The group said that in May 2014 two of its enterprises in the anti-terrorist operation (ATO) zone were stopped from operating – Stirol Concern and Severodonetsk Azot, and Cherkasy Azot and Rivneazot were loaded as much as possible.

"However, the further deliberate fabrication of some criminal cases against officials of Ostchem's enterprises and against the enterprises and the absolutely illegal arrest of the key raw material of the enterprises – gas – deprived these enterprises of a chance to operate," Group DF said.