More than 9,000 people have died in 21 months of fighting in eastern Ukraine, even as a new cease-fire has largely held and contributed to a sharp decline in casualties since mid-August, the U.N. human rights office said Wednesday.

The office of High Commissioner for Human Rights said a "cease-fire within a cease-fire" agreed in late August and subsequent withdrawal of heavy weapons from front lines has calmed violence between government forces and pro-Russian separatists.

OHCHR cautioned in its 12th monitoring report on the Ukraine conflict that skirmishes in early November along the contact line have fanned fears of a possible resumption of shelling of population centers.

The report, covering Aug. 16 to Nov. 15, said 9,098 people including combatants and civilians have now died in the conflict in eastern Ukraine since April last year - including 47 civilians in that three-month period. The total is up from 7,883 tallied in the previous quarterly report released in September.

"This increase of almost 1,200 killed and over 3,000 injured is because of the counting that is made by official authorities, especially the Ministry of Defense and the Ministry of Interior," said Gianni Magazzeni, a senior U.N. official involved in the report.

However, he noted that "there remain a large number of unidentified bodies in morgues, in multiple places, especially in the areas controlled by armed groups."

Since the report's cutoff date of Nov. 15, six people have been killed and 21 have been wounded, Magazzeni told reporters in Geneva.

"After more than 9,000 people have lost their lives, the reduction in hostilities, and thus in new casualties, is very welcome," said U.N. human rights chief Zeid Raad al-Hussein. "I urge all sides to fully implement the Minsk agreements and to actively work to ensure the application of the rule of law and international human rights norms everywhere in Ukraine."

But he said many problems remain for residents of eastern Ukraine.

"Civilians in the conflict-afflicted eastern parts of Ukraine end the year as they began it, in a very difficult humanitarian and human rights situation," he said. "Elderly people have no access to their life savings, people with disabilities have little assistance, and reduced access to health care has left many in dismal, precarious, even life-threatening situations."