The head of Moldova’s breakaway region Transnistria has urged residents to burn firewood for heating and warned that blackouts cannot be avoided, after Moscow stopped supplying gas via Ukraine.

More than 51,000 households were left without gas and 1,500 apartment buildings had no winter heat in Moldova's pro-Russian separatist enclave, authorities said on Monday, after Ukraine refused to extend a transit agreement with Russia last week.

Russia’s state-owned energy giant Gazprom says it will halt gas supplies to Moldova starting on Jan. 1, citing alleged unpaid debt by the east European country.