GENEVA (AFP) - The United Nations said Monday that more than 6,400 people had been killed in conflict-wracked Ukraine, and despite a slowdown in fighting, millions more are suffering from abuses and hardship.

In its latest report, the UN human rights office noted that an overall decrease in indiscriminate shelling since a fragile truce was agreed in Minsk in February had resulted in a decrease in civilian casualties.

But nonetheless, at least 6,417 people perished from the beginning of the conflict in mid-April 2014 through May 30, 2015, including at least 626 women and girls, while another 15,962 had been wounded, it said.

"This is a conservative estimate and the actual numbers could be considerably higher," the rights office said in a statement.

Some five million others are meanwhile suffering the consequences of the conflict, including 1.2 million people who have been displaced inside the war-ravaged country, the report said.

"Even with the decrease in hostilities, civilians continue to be killed and wounded," U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein said.

"We have documented alarming reports of summary executions by armed groups and are looking into similar allegations against Ukrainian armed forces," he said, also decrying "horrific accounts of torture and ill-treatment in detention" by both sides.

Civilians in the areas under the control of armed groups are facing "serious rights abuses," including "killings, torture and ill-treatment," as well as detention, "forced labor, looting, ransom demands and extortion," the report said.