GENEVA - A new report accuses Turkey’s security forces of widespread and systematic human rights violations, including massive destruction of towns and killings of mainly Kurdish people in the southeast.

Turkey has denied repeated requests for access to the country by U.N. human rights investigators, so they have been forced to gather evidence through satellite imagery and interviews.

The report documents accounts of torture, enforced disappearances, violence against women and other human rights violations committed between July 2015 and December 2016 in southeast Turkey.

During that period, the report says government security operations displaced between 355,000 and one-half-million, mainly Kurdish people in more than 30 towns and neighborhoods.

The report describes the destruction of buildings in some villages. In one area, local authorities estimate 70 percent of the buildings were systematically destroyed by shelling.

U.N. human rights spokesman Rupert Colville said heavy damage also has been reported from other towns, including Cizre, in Sirnak Province.

“The report," said Colville, "describes how witnesses and family members of victims 'painted an apocalyptic picture of the wholesale destruction of neighborhoods' where, in early 2016, up to 189 men, women and children were trapped for weeks on end in basements without water, food, medical attention and power before being killed by fire, that had apparently been caused by shelling.”

The report cites information received from the Turkish government accusing the Kurdistan Workers Party, or PKK, which it considers a terrorist organization, of conducting violent attacks that killed and injured Turkish security forces and other individuals.

U.N. High Commissioner for Human Rights Zeid Ra-ad al-Hussein said he is alarmed at the ongoing deterioration of human rights since an attempted coup last July in Turkey. The human rights chief said he is particularly concerned that there has been no credible investigation of the hundreds of alleged unlawful killings, including those of women and children.

Given the magnitude of the alleged crimes, he said an independent investigation is both urgent and essential.