KIEV, Dec 17 (Reuters) - Some 20 power units across Ukraine have been idled due to a lack of coal and the latest data shows coal reserves at plants have fallen by another four percent, state-run energy firm Ukrenergo said on Wednesday.
Ukraine used to be self-sufficient in coal, but separatist fighting in the Donetsk and Luhansk regions has halted production at more than half of the country's coal mines, prompting a power crisis.
Coal reserves at power plants have fallen to 1.39 million tonnes, Ukrenergo said, down from around 4 million tonnes a year ago.
The 20 idled units at six thermal power plants represent a capacity of 5,400 megawatts or around 10 percent of Ukraine's total power capacity.
The resulting electricity shortages have forced the company to impose power restrictions across the country.
Ukraine has looked to buy thermal coal from abroad, but supplies from Russia have been erratic and a deal to import South African coal fell through.
Thermal power plants traditionally supply around 40 percent of Ukraine's electricity. (Reporting by Pavel Polityuk; editing by Alessandra Prentice and Jason Neely)