Finns should be prepared for power outages caused by possible electricity shortage in the coming winter, national grid operator Fingrid said in an updated assessment on Monday.

Finland, reliant on importing electricity to ensure reliable supplies, has seen its ability to import power from Sweden weakened after utility Vattenfall earlier this month delayed the restart of the Ringhals 4 nuclear reactor by two months.

"As a result of great uncertainties, Finns should be prepared for power outages caused by a possible power shortage in the coming winter," it said in its new assessment. (Reporting by Stine Jacobsen, editing by Terje Solsvik)