An average of 13 people have been killed daily in eastern Ukraine since a 5 September ceasefire came into place, the UN human rights commissioner says.
In the eight weeks since the shaky truce came into force, the UN says 957 people have been killed, amid continuing violations on both sides.
The commissioner’s report describes a total breakdown of law and order in rebel-held Donetsk and Luhansk.
It also highlights credible allegations of abuses by government forces.
Conflict broke out in eastern Ukraine last April, when the government in Kiev launched an operation to recapture areas seized by pro-Russian rebels.
The separatists took over public buildings, after Russia responded to similar moves by rebels in Crimea by annexing the peninsula.
As part of the truce signed in the Belarusian capital, Minsk, monitors from the European security body, OSCE, were to observe the eastern areas and the borders with Russia.
The monitors themselves complained they had come under fire on Wednesday, from uniformed soldiers operating near a government-held area.
Two shots were fired at the OSCE convoy near Mariinka, 15km (9 miles) west of Donetsk, from a distance of 80m, the OSCE said, but no-one was hurt.
An OSCE spokeswoman refused to speculate on whether Ukrainian government soldiers had been to blame.
The UN team in Ukraine said on Thursday that 4,317 people had been killed since the conflict erupted in April.
There has also been a substantial rise in the number of internally displaced people in Ukraine in the past two months, up from 275,489 to 466,829.
The human rights situation is directly affected, the report says, by the large amount of weapons and the foreign fighters “that include servicemen from the Russian Federation”.