Hundreds of people across the country were killed or wounded in drone and missile strikes in the 10-day period between 29 December and 8 January alone.
“Civilian casualties had been steadily decreasing in 2023 but the wave of attacks in late December and early January violently interrupted that trend,” said Danielle Bell, head of the monitoring mission.
HRMMU verified that at least 592 civilians were killed or injured last month, a 26.5 per cent increase over November, representing “an alarming reversal of a downward trend” observed earlier in 2023.
However, the actual increase is likely higher as some casualty reports are yet to be verified.
The high number of civilian casualties in December continued into the first days of January, and HRMMU is verifying reports of 86 killed and 416 injured.
The recent wave of attacks started on 29 December with missiles and drones that pounded cities and towns across Ukraine.
The most extensive attacks and the highest numbers of civilian casualties happened on that day and on 2 January but fatalities have continued.
HRMMU cited examples such as the 6 January missile attack on the small town of Pokrovsk and nearby Rivne village, located near the frontline in the east.
Two families – six adults and five children – were buried in rubble after their homes were struck. Some of the bodies are still missing despite days of rescue and recovery efforts.
In a separate attack two days later in Novomoskovsk, also in the east, the blast wave from a Russian missile strike injured 31 civilians, including eight passengers on a minibus which was destroyed during the morning commute.
Next month marks two years since Russia launched its full-scale invasion of Ukraine, which has left 40 per cent of the population, 14.6 million people, in need of humanitarian assistance.
More than four million people are internally displaced and 6.3 million have sought refuge elsewhere, mainly in neighbouring countries.
On Monday, the UN launched a $4.2 million appeal to support humanitarian operations this year.