The Thursday report issued by UN human rights chief Michelle Bachelet accused the Venezuela government of using a strategy of instilling fear in its population to retain power and removing opponents with a "shocking" number of alleged extrajudicial killings.
Venezuela's government slammed the report as "distorted and biased", the BBC reported.
Government figures showed deaths ascribed to criminals resisting arrest numbered 5,287 in 2018 and 1,569 by May 19, 2019. However, the UN report suggested that many of these deaths were actually extrajudicial executions.
Victims are arrested and shot, with crime scenes manipulated to suggest they resisted the police, said the report. It will be presented to the UN Human Rights Council on Friday.
It is based on "558 interviews with victims and witnesses of human rights violations and the deteriorating economic situation" from January 2018 to May 2019, according to the BBC.
The report said the killings were part of a strategy by the government of President Nicolas Maduro aimed at "neutralizing, repressing and criminalizing political opponents and people critical of the government".
Maduro is locked in a political battle with opposition leader Juan Guaido. The latter, head of the country's National Assembly, declared himself interim President in January and has the backing of over 50 countries, including the US and most of Latin America.
On the other hand, Maduro retains the loyalty of most of the military and allies such as China and Russia.
The UN says that some four million people have fled Venezuela since 2015, amid a severe economic crisis that has resulted in high unemployment and chronic shortages of food and medicine.
According to the UN, witnesses reported how the Special Action Forces (FAES) "manipulated the crime scene and evidence. They would plant arms and drugs and fire their weapons against the walls or in the air to suggest a confrontation and to show the victim had 'resisted authority'."
The report added that the UN is "concerned the authorities may be using FAES and other security forces as an instrument to instil fear in the population and to maintain social control".
Responding to the report, the Venezuelan government said the UN was wrong to say that the state was not investigating alleged human rights violations, adding that several suspects had been imprisoned.
The report also covers economic and social rights, and social programmes and policies. A separate section covers the rights of indigenous people, migrants and refugees.
The UN said that "there are reasonable grounds to believe that grave violations of economic and social rights, including the rights to food and health, have been committed in Venezuela".
On accusations of torture, it says that detainees have been subjected to "one or more forms of torture or cruel, inhuman or degrading treatment or punishment, including electric shocks, suffocation with plastic bags, water boarding, sexual violence... and exposure to extreme temperatures".
( With inputs from IANS )