The reports coincide with intensive talks overseen by US President Donald Trump and aimed at bringing an end to the nearly four-year-old war. Each country has said the other is doing all it can to influence his views and shape the outcome.
"On New Year, Russia deliberately brings war. Over 200 attack drones were launched onto Ukraine in the night," Ukrainian President Volodymyr Zelenskiy wrote social media, saying energy infrastructure in seven regions across Ukraine had been targeted.
Russia accused Ukraine of killing at least 24 people, including a child, in a drone strike on a hotel and cafe where civilians were seeing in the New Year in a Russian-controlled part of the Kherson region in southern Ukraine.
Ukraine's military, which has accused Russia of killing many civilians in its own attacks on Ukrainian cities, said it targeted strictly military and energy targets, but made no specific reference to accounts of the strike on the hotel.
Zelenskiy said Russia's holiday season attacks showed Ukraine could not afford delays in air defence supplies.
"(Our) allies have the names of equipment which we are lacking. We expect that everything agreed with the United States at the end of December for our defence will arrive on time," he said, without clarifying further.
Vladimir Saldo, the Russian-installed governor of the region, said three Ukrainian drones had hit the celebrations in Khorly, a coastal village, in what he said was a "deliberate strike" against civilians.
He said that many people had been burnt alive.
Russia's Foreign Ministry said as well as the 24 dead, 50 people had been injured.
It said the strike, as well as other drone attacks blamed on Ukraine, sought to "divert attention from the failures of the Ukrainian military at the front. The Kyiv regime is trying to prove its viability through terrorist acts."
On Monday, Moscow accused Kyiv of trying to strike a residence of President Vladimir Putin. Ukrainian and European officials have said the incident did not happen and US security officials were also reported to have found that Ukraine did not target the residence.
A senior Russian military chief handed to a US military attaché what he said was part of a Ukrainian drone containing data he said proved that the Ukrainian military had targeted the residence.
Reuters was not able to immediately verify the reported Kherson region attack or photographs of what Saldo's press service said was the aftermath. Saldo said he had briefed Putin on the details of the attack.
The images showed at least one dead body was visible beneath a white sheet. The building showed signs that a fire had raged and there were what looked like blood stains on the ground. Russia's TASS news agency published video showing drone fragments, some with Ukrainian writing on them.
Ukrainian officials regularly report civilian deaths from Russian air attacks, including in the Ukrainian-held city of Kherson, which lies near the front line.
The Ukrainian governor of Kherson region, Oleksandr Prokudin, said one man had been killed and an 87-year-old woman injured in attacks on the city on Thursday.
The Russian Defence Ministry said its strikes had hit military targets, as well as energy infrastructure which it claimed was being used to support Ukraine's military.
Dmitry Medvedev, deputy chairman of Russia's Security Council, told TASS that those who carried out the hotel attack and their commanders should be targeted.
Kherson is one of four regions in Ukraine which Russia claimed as its own in 2022, a move Kyiv and most Western countries denounced as an illegal land grab.
