Russia hit about 30% of Ukraine's energy infrastructure in its missile attacks on Monday and Tuesday, Ukraine's Energy Minister Herman Halushchenko told CNN in an interview.
"We send this message to our partners: we need to protect the sky," Halushchenko told CNN late on Tuesday, adding that Russia was disregarding international rules.
"They don't care about any kind of international agreements or conventions."
Ukraine urged civilians on Tuesday not to use domestic appliances like ovens and washing machines to save electricity as millions faced blackouts after the biggest Russian attack on its energy network since war broke out.
Moscow, which calls its actions in Ukraine a "special military operation" to eliminate dangerous nationalists and protect Russian speakers, has accused the West of escalating and prolonging the conflict by supporting Kyiv.