Ukraine's gas debt to Russia will be almost $2 billion if the country fails to pay for February deliveries in full.
Speaking at a press conference, Russian President Vladimir Putin said that Ukraine's current debt stands between $1.5bn and $1.6bn.
Earlier, Russia's top gas producer Gazprom said it would remove a discount on gas prices for Ukraine starting from April.
More top news
Big Ben will fall silent on Monday for renovations following a backlash from MPs over the proposed four-year timetable for the work.
Rain will push into the northwest, turning heavy and persistent in places
Thousands of dangerous appliances are still in use across the UK despite years of warnings about the dangers.