Russia carried out a “massive strike” on critically important energy facilities of Ukraine’s military-industrial complex on Friday, the Russian defence ministry said on Saturday.

In a daily update, the ministry did not identify the energy facilities it claimed to have hit. It said the strike had also blocked the transport of foreign weapons and ammunition by rail to battlegrounds in Ukraine.

Ukraine’s armed forces said late on Friday that Russian forces had fired more than 100 missiles and mounted 12 air and 20 shelling attacks. It said 61 Russian cruise missiles were destroyed.

Ukraine’s energy minister German Galushchenko said Russia had hit power facilities in six regions with missiles and drones, causing blackouts across most of the country.

Russia has repeatedly attacked civilian infrastructure far from the front lines, leaving millions of Ukrainians without power, heat or water for days.

‘War to drag on’

The owner of the Russian Wagner Group private military contractor actively involved in the fighting in Ukraine has predicted that the war could drag on for years.

Yevgeny Prigozhin said in a video interview released late on Friday that it could take 18 months to two years for Russia to fully secure control of Ukraine’s eastern industrial heartland of Donbas. He added that the war could go on for three years if Moscow decides to capture broader territories east of the Dnieper River.

The statement from Prigozhin, a millionaire who has close links to Russian President Vladimir Putin and was dubbed “Putin’s chef” for his lucrative Kremlin catering contracts, marked a recognition of the difficulties that the Kremlin has faced in the campaign, which it initially expected to wrap up within weeks when Russian troops invaded Ukraine on February 24.

Russia suffered a series of humiliating setbacks in the fall when the Ukrainian military launched successful counteroffensives to reclaim broad swaths of territory in the east and the south.

The Kremlin has avoided making forecasts on how long the fighting could continue, saying that what it called the “special military operation” will continue until its goals are fulfilled.

The Russian forces have focused on Ukraine’s Luhansk and Donetsk provinces that make up the Donbas region where Moscow-backed separatists have been fighting Ukrainian forces since 2014.

Ukrainian and Western officials have warned that Russia could launch a new broad offensive to try to turn the tide of the conflict as the war approaches the one-year mark. But Ukraine’s military intelligence spokesman, Andriy Chernyak, told Kyiv Post that “Russian command does not have enough resources for large-scale offensive actions.”

“The main goal of Russian troops remains to achieve at least some tactical success in eastern Ukraine,” he said.

Prigozhin said that the Wagner Group mercenaries were continuing fierce battles for control of the Ukrainian stronghold of Bakhmut in the Donetsk region. He acknowledged that the Ukrainian troops were mounting fierce resistance. As Russian troops have pushed their attacks in the Donbas, Moscow has also sought to demoralise Ukrainians by leaving them without heat and water in the bitter winter.

On Friday, Russia launched the 14th round of massive strikes on Ukrainian energy facilities and other vital infrastructure.

High-voltage infrastructure facilities were hit in the eastern, western and southern regions, resulting in power outages in some areas. Ukraine’s energy company, Ukrenergo, said Saturday that the situation was “difficult but controllable”.