Ukraine introduced emergency power cuts in six regions amid what authorities described as a "massive" Russian missile strike, the national grid operator said on Wednesday.

Ukraine is under a massive raid red alert early on Wednesday amid reports of a large-scale attack launched by Russia. Air raid alerts indicate that there is a potential threat of an attack. The alerts may be issued when Russian warplanes take off,

Ukraine struck Russian regions with a major drone and missile attack overnight, damaging at least two factories and forcing schools to close in a major southern Russian city, according to Russian officials and media.

Ukraine fired six US-made ATACMS ballistic missiles, six British Storm Shadow cruise missiles and at least 146 drones into Russia in a mass attack, says Moscow. It threatened retaliation against the air strikes.

Ukraine used six British Storm Shadow missiles and US-made Atacms tactical ballistic missiles in what Kyiv described as its “largest attack” on Russian military facilities.

Russia said on Monday it had downed nine Ukrainian drones that tried to attack part of the infrastructure of the TurkStream gas pipeline, through which Russian gas flows to Turkey and Europe, and called the attack an "act of energy terrorism".

Russia’s military on Tuesday said it would retaliate against Ukraine after Kyiv attacked Russian regions by firing six US-made ATACMS ballistic missiles, six UK-made Storm Shadow cruise missiles and launching one of the biggest drone attacks to date.