Russia’s Gazprom has asked that a bill for $5.319 billion sent to Ukraine’s Naftogaz Ukrayiny on January 17 be added to its list of claims against the state-owned Ukrainian company currently before the Stockholm arbitration court, Gazprom’s press service said Monday.

Gazprom charged Naftogaz for gas not taken in 2016 under the take-or-pay terms of a 10-year gas supply contract signed in 2009 and gave Naftogaz 10 days to pay, according to platts.com.

Naftogaz said it would refuse to pay anything to Gazprom until a ruling from the Stockholm court.

With the 10-day deadline now passed, Gazprom said it had requested the new additional amount be considered by the Stockholm court.

Before the latest bill, Gazprom was claiming some $39 billion from the Ukrainian company, while Naftogaz, in its own claims to the court, was seeking $28 billion from Gazprom, saying it had been overcharged since 2010.

A ruling from the court, which began addressing all of the claims at the end of 2016, is due in June.

If the court considers the latest bill too it would bring Gazprom’s claims to more than $44 billion.