KIEV - Russia has begun to restrict coal supplies to Ukraine, Energy Minister VolodymyrDemchyshyn told parliament on Friday, days after the Kremlin threatened to punish Kiev for a power blackout of Russian-annexed Crimea.

Demchyshyn said pro-Russian separatists who control coal mines in eastern Ukraine had also halted coal supplies. He said Kiev had one month of its own coal supplies left and was seeking alternative supplies from South Africa.

"Coal supplies have been restricted from uncontrolled territory (Donbass) and from Russia," said Demchyshyn.

"Right now our power stations have enough coal reserves in storage to last for at least one month. But in the long-term problematic questions will arise."

Russian Energy Minister Alexander Novak said on Tuesday that Russia might cut coal supplies to punish Ukraine for what he said was its deliberate refusal to help rebuild power lines to Crimea, which were blown up by unknown saboteurs.

Russia seized Crimea from Ukraine in March last year, plunging relations between the one-time allies into crisis.

Minor repair work has been carried out on the sabotaged pylons and power lines in southern Ukraine which supply Crimea, but none of the four pylons which were destroyed are operational.

Ukraine depends on coal to fulfil around 44 percent of its power needs. Nuclear energy makes up about the same proportion, with the rest of its needs being met by renewable sources.(Reuters)