Flows of Russian gas via Ukraine to central and eastern Europe stopped on New Year's Day after a transit deal expired between the warring countries and Kyiv refused to extend it.
Transdniestria, a mainly Russian-speaking enclave which has lived side-by-side with Moldova since breaking away from it in the last days of Soviet rule, received gas from Russian giant Gazprom through the pipeline crossing Ukraine.
The gas was used to operate a thermal plant which provided electricity locally and for much of Moldova under the control of the pro-European central government.
The region's self-styled president, Vadim Krasnoselsky, writing on the Telegram messaging app, said rolling power cuts in various districts would be extended to four hours on Sunday.
Hour-long cuts were first imposed on Friday evening after heating and hot water supplies were curtailed. The cuts were then extended to three hours on Saturday.
"Yesterday's introduction of rolling cuts was a test. And it confirmed that an hour-long break to keep the electrical supply system operating was insufficient," Krasnoselsky wrote. "The power generated is not covering sharply rising demand."
All industries except those producing food have been shut down. The official Telegram news channel of the region's separatist authorities announced the official closure on Saturday of a steel mill and bakery in the town of Rybnitsa.
Regional officials announced new measures to help residents, especially the elderly, and warned that overnight temperatures would fall to -10 Celsius. Residents were told not to put strain on the region's mobile phone network.
The news channel warned against using heaters in disrepair after two residents died of carbon monoxide poisoning from a stove. Online pictures showed servicemen loading up trucks with firewood for distribution.
"Don't put off gathering in firewood," Krasnoselsky told residents. "It is better to ensure your supply in advance, especially since the weather is favourable so far."
Moldova's government blames Russia for the crisis and has called on Gazprom to ship gas through the Turkstream pipeline and then through Bulgaria and Romania.
Russia denies using gas as a weapon to coerce Moldova, and blames Kyiv for refusing to renew the gas transit deal.
The Transdniestria power cuts are a problem for Moldova particularly because the enclave is home to a power plant which provides most of the power for government-controlled areas of Moldova at a fixed and low price.
Prime Minister Dorin Recean said on Friday his country faced a security crisis after Transdniestria imposed the rolling blackouts, but he also said the Chisinau government had prepared alternative arrangements, with a mixture of domestic production and electricity imports from Romania.
Even before the halt of supplies via Ukraine, Gazprom had said it would suspend exports to Moldova on January 1 because of what Russia says are unpaid Moldovan debts of $709 million. Moldova disputes that and put the figure at $8.6 million.
