Russia says there is a risk that gas shortages this winter could force Ukraine to siphon off supplies of Russian gas meant for EU customers.
Ukraine’s gas reserves have reached a “critical” state, Russian Energy Minister Alexander Novak said.
He was speaking after talks in Moscow with EU Energy Commissioner Guenther Oettinger. The EU is anxious to ensure secure gas supplies for the winter.
Ukraine needs to store much more gas underground, Mr Novak said.
He estimated at 10bn cubic metres (353bn cu ft) the amount of extra gas that Ukraine would need to pump into underground storage tanks to avoid having to siphon off gas from the transit pipelines.
In winter, he warned, “there will be big risks, above all the possibility of Ukraine taking gas to meet its own needs, instead of those supplies going to European customers”.