Russia attacked Ukraine with more than 200 missiles and drones on Monday, killing seven people and striking energy facilities nationwide, Kyiv said, while neighbouring NATO member Poland reported a drone had probably entered its airspace, Paralel.Az reports citing Reuters.

Power cuts and water supply outages were reported in many areas, including parts of Kyiv, as officials said the attack - 2-1/2 years since the full-scale invasion - targeted power or other critical infrastructure across the country.

Russia stepped up its strikes on the Ukrainian power grid in March in what Kyiv has said looked like a concerted effort to degrade the system ahead of next winter when people need electricity and heating most.

The air force downed 102 out of 127 incoming missiles and 99 out of 109 drones, Air Force Commander Mykola Oleshchuk said on Telegram, describing the attack from the air, ground and sea as "the most massive" of the war.

According to Prime Minister Denys Shmyhal, 15 regions sustained damage. President Volodymyr Zelenskiy said there was "a lot of damage in the energy sector".

U.S. President Joe Biden condemned, opens new tab Russia's strikes as "outrageous." In a statement on Monday, he added that Washington will continue surging energy equipment to Ukraine to repair its systems and to support Ukraine's energy grid.

Zelenskiy said he had discussed Ukraine's response to the attack with his top commander: "We are preparing it."

Russia's defence ministry said its forces used high precision weapons to strike important energy infrastructure in Ukraine which it said supported the military-industrial complex. It listed power substations, gas compressor stations and storage sites for aircraft weapons.

Ukraine has claimed new ground in a major cross-border incursion into Russia's western Kursk region while Russian forces steadily have inched forward in Ukraine's east, closing in on the transport hub of Pokrovsk.

After meeting top officials, Zelenskiy said a decision had been taken "further strengthen" the Pokrovsk front, which saw at least 56 combat clashes on Monday, according to the military.