Ukraine on Friday accused Russia of reducing its coal deliveries to Kiev in a move that could further ratchet up tensions with Moscow.

"Coal deliveries from the territories that are not under our control and from Russia have been reduced," Ukrainian Energy Minister Volodymyr Demchyshyn told parliament, referring to the eastern parts of the country that are controlled by pro-Russian separatists.

The latest rise in tensions between Kiev and Moscow follows Russian Energy Minister Alexander Novak's threat on Tuesday to suspend coal supplies to Kiev after explosions on power lines coming from Ukrainian territory left the Russian-annexed Crimean peninsula without electricity.

The explosions -- orchestrated by unknown attackers -- last week left some 1.6 million people in the dark and further infuriated Moscow as Kiev expects its free-trade agreement with the EU to come into force from January 1, 2016.

"Russia's goal is to destabilise Ukraine," Ukrainian Prime Minister Arseny Yatsenyuk said on Friday.

Russia last week threatened to introduce a blanket ban on food supplies from Ukraine starting next year, saying Kiev's landmark agreement with the EU would damage Moscow's economic interests.

The pro-Russian rebels -- who control the eastern areas where most of Ukraine's coal mines are located -- this week announced an embargo on coal supplies to the rest of Ukraine.

Kiev and its Western allies accuse Moscow of supporting the pro-Russian insurgency in eastern Ukraine in a conflict that has now killed more than 8,000 people.

Demchyshyn said Ukraine currently had coal reserves for a month and would extend this period to 50 days thanks to coal supplies scheduled to arrive from South Africa in early December.

Last winter, the shortage of anthracite coal that many Ukrainian power plants use had caused power cuts and forced Kiev to sign electricity and coal supply contracts with Russia amid the unprecedented crisis in bilateral relations.