The press service of the Ukrainian company said that the use of "take or pay" principle by Gazprom was illegal in this case.

KIEV, January 19. /TASS/. Naftogaz of Ukraine has refused to pay the bill of $2.59 billion it received from Russian gas giant Gazprom.

"Naftogaz of Ukraine considers the provision of take or pay in the form it was set out in the contract with Gazprom to be non-market, illegal and invalid. The validity of the claims of Gazprom based on "take or pay" principle will be determined in court," - according to the statement.

Naftogaz of Ukraine challenges the application of that provision in the Court of the Arbitration Institute of the Stockholm Chamber of Commerce.

Earlier on Tuesday, Gazprom drew a $2.549 bln bill to Naftogaz of Ukraine for the Russian gas Ukraine had not taken in the third quarter of 2015 under "take or pay" condition.

Gazprom expects the Ukrainian company to pay the bill in 10 days.

Under the current contract signed between Gazprom and Naftogaz of Ukraine, the buyer is obliged to annually pay for a minimal annual volume of gas. According to the contract, the minimum gas volume in the third quarter of 2015 was 10.485 bln cubic meters.

Taking into account this provision as well as the volume of gas supplied to Ukraine in the third quarter of 2015, Gazprom drew a bill for the sum of $2.549 bln to the Ukrainian company.

"In 2015, Ukraine actually refused to buy the Russian gas in the third quarter and there was no agreement that "take or pay" rule is not applied in that period," - Gazprom CEO Alexey Miller said.

In 2015, "take or pay" rule was not valid for "Naftogaz of Ukraine" in the 1st, 2nd and 4th quarters.