"Civilians continue to suffer seriously as a result of the protracted conflict," UN High Commissioner for Human Rights (OHCHR) spokesperson Ravina Shamdasani told reporters in Geneva today. "In 2015 alone, about 400 civilians have been killed as a result of indiscriminate shelling of residential areas and because of landmines and unexploded ordnance – both in Government-controlled territories and in territories controlled by armed groups."

According to reports, fighting has intensified, especially in the vicinity of the Donetsk airport and near the village of Shyrokine in the Donetsk region, where heavy weapons, including mortars, artillery and tanks are reportedly extensively used – running counter to the Minsk Accords.

"In one day alone, on 13 April, the Ukrainian armed forces reported six servicemen killed and 12 wounded," said Ms. Shamdasani. "While the self-proclaimed 'Donetsk people's republic' and self-proclaimed 'Luhansk people's republic' claimed four of their fighters were killed and 17 wounded. We fear a further escalation of hostilities."

The UN Human Rights Office and the World Health Organization estimate that since April 2014, at least 6,116 people, both military personnel and civilians, have been killed and 15,474 wounded. The actual number of casualties could be considerably higher, as hundreds remain missing and hundreds of bodies are still pending recovery.

As well as pointing to the thousands of civilian deaths, Ms. Shamdasani also highlighted the killings of former parliamentarian Oleh Kalashnikov and of two journalists, Oles Buzyna and Serhiy Sukhobok, which it said were "very disturbing" and which required "swift, independent and credible" investigations to ensure justice and accountability for those responsible.

"The protection of civilians must be considered the utmost priority," she said. "Those committing violations of human rights and international humanitarian law, in any part of the country and by any side to the conflict, must be held accountable."

The impact of the conflict on civilians went beyond the direct destruction and death experienced by many, according to the press release. The conflict also continues to affect the daily lives of people in conflict-affected zones and elsewhere in Ukraine.

"The proliferation of arms, the lack of job opportunities, limited access to medical and psychological rehabilitation, particularly for more than 20,000 demobilised soldiers, and a deep anxiety that the ceasefire may not hold all have a serious impact on the population," Ms Shamdasani said.

In late February 2014, the situation in Ukraine transcended what was initially seen as an internal Ukrainian political crisis into violent clashes in parts of the country, later reaching full-scale conflict in the east. Despite a September 2014 cease-fire agreed in Minsk, the situation in Ukraine has since continuously deteriorated, with serious consequences for the country's unity, territorial integrity and stability. In February 2015, the parties in Ukraine and the Trilateral Contact Group signed a "Package of Measures for the Implementation of the Minsk Agreements."