More than 330 people have been killed in Ukraine since a fragile truce began a month ago, with five million people affected by continuing violence, the United Nations said Wednesday.
A report from the UN rights agency also found that before the September 5 ceasefire, pro-Russian rebels in eastern Ukraine had seen their numbers significantly bolstered by an influx of foreign fighters, including apparently Russian citizens.
"While the ceasefire is a very welcome step towards ending the fighting in eastern Ukraine, I call on all parties to genuinely respect and uphold it, and to halt the attacks on civilians and civilian infrastructure once and for all," UN rights chief Zeid Ra'ad Al Hussein said in a statement.
His office said 331 deaths were recorded between September 6 and Monday, although it stressed that some of those deaths may have occurred before the peace pact was signed in Minsk on September 5 but were not logged until afterwards.
That amounts to just over 10 deaths per day on average, said Gianni Magazzeni, who heads the rights agency's Americas, Europe and Central Asia branch.
That is about the same as the average toll from April through June of 11 deaths per day, before it rose to around 30 per day in July and soared to 42 per day just before the signing of the truce, he noted to reporters in Geneva.
Mortar and shelling attacks have meanwhile killed 14 civilians since the weekend -- one of the deadliest spells in six months of fighting that has killed nearly 3,400 people across the mainly Russian-speaking east.
Counting the 298 people who died in the downing of Malaysian Airlines flight MH17 over Ukraine in July, the overall toll stands at 3,660 deaths as of Monday, the UN rights office said.
As of mid-September, at least 36 children had been killed in the fighting, and at least 82 figured among the nearly 8,200 wounded.
Magazzeni stressed though that the overall tally was "very conservative", and that "the actual figure certainly will be much higher."
Reports of mass graves
He said the team of 35 UN rights monitors on the ground had recently been receiving reports of mass graves with a total of around 400 bodies in parts of the Donetsk region that had been under control of both pro-Russian rebels and Ukrainian forces.
But the UN monitors did not gain access to the area and were unable to verify the reports, he said, calling for an independent investigation, including by forensic experts.
In its latest report covering the period from August 18 to September 16, Zeid's office meanwhile found that before the ceasefire, "an increasing number of foreign fighters were reported to be participating in the fighting, including citizens of the Russian Federation."
It said that former Russian servicemen and active duty personnel on leave were allegedly among them.
During the period covered by the report, pro-Russian armed groups had "continued to terrorize the population in areas under their control, pursuing killings, abductions, torture, ill-treatment and other serious human rights abuses, including destruction of housing and seizure of property," it said.
It also detailed continued allegations of human rights violations by some pro-Kiev volunteer battalions.
Between August 24 and September 5, the report also noted "a sharp increase in detentions by the armed groups" on the pro-Russian side, as well as "alarming reports of torture and ill-treatment of detainees, including mock executions and sexual violence."
People held by Ukrainian armed forces and police had also faced ill-treatment, according to the report, which also noted that hundreds of people had been reported missing or abducted.
More than five million people live in areas affected by the violence, which is curtailing their basic human rights to things like education and housing, Zeid said.
Especially vulnerable are the nearly 375,800 people who as of October 2 have been displaced inside Ukraine by the fighting, the statement said.