Russia's Gazprom demanded a $1.66 billion pre-payment from Ukraine for June gas deliveries on Tuesday, saying the neighbouring country had only half its requirements in storage to ensure a trouble-free winter, Reuters reports.
"Taking into account non-working days, Naftogaz should pay this bill by June 2 and, starting from June 3, the company will be getting gas ... only at the volumes paid for," spokesman Sergei Kupriyanov said in a statement.
This means that Ukraine needs to pay $1.658 billion for June's gas deliveries based on a price of $485 per 1,000 cubic metres, he added.
Ukraine wants to change the conditions of a 2009 contract that locked Kiev into buying a set volume, whether it needs it or not, at $485 per 1,000 cubic metres - the highest price paid by any client in Europe.
Kiev has so far refused to pay the higher price, saying gas is being used as a political tool by Moscow to punish Ukraine's new leaders for moving closer to the European Union.