Europe may start selling natural gas to Ukraine at market prices of $370-400 per 1,000 cubic meters in case they resume reverse supplies. The money equals the price tag that Russia's energy giant Gazprom put on its gas deliveries to Ukraine before the agreed discount. This is according to Ukraine's energy ministry Yuri Prodan.

"Gas should be sold at market prices. They range from around $370 per 1,000 cubic meters to some $400," he said.

Last December, Russia and Ukraine agreed to slash gas prices for Kiev in 2014 to $268.5, but this deal was to be re-affirmed every four months.

In 2013, Ukraine's state-run Naftogas received some 13 billion cubic meters from Russia at $400 on average.

According to Prodan, starting on April 1, Gazprom's prices for Ukraine's gas deliveries may hike up to $380 per 1,000 cubic meters.