The Energy and Coal Industry Ministry of Ukraine is trying to unblock supplies of 500 trucks with Russian coal, which have been stopped at the border and have already been paid for by Ukraine, though without much success, Energy and Coal Industry Minister Volodymyr Demchyshyn has said.

"There are certain delays with coal transportation from Russia: around 500 wagons are staying on the border. We've fulfilled our payment liabilities in full," he said at a briefing in Kyiv on Friday.

"I'm trying to reach the highest level," the minister said.