Venezuela's president and top ministers are responsible for probable crimes against humanity including extrajudicial killings and the systematic use of torture, UN investigators said on Wednesday.

In their first report, the team tasked with probing a slew of alleged violations  said they had found evidence that state actors, including President Nicolas Maduro, were behind serious crimes.

The International Fact-Finding Mission, created by the UN Human Rights Council a year ago, "found reasonable grounds to believe that Venezuelan authorities and security forces have since 2014 planned and executed serious human rights violations," mission chairperson Marta Valinas said.

Some of those violations, "including arbitrary killings and the systematic use of torture, amount to crimes against humanity," said Valinas, whose three-person team was unable to enter Venezuela but relied on remote interviews with victims, witnesses and others, as well as analysis of legal files.

"Far from being isolated acts, these crimes were coordinated and committed pursuant to state policies, with the knowledge or direct support of commanding officers and senior government officials." 

The 411-page report identified the Venezuelan officials deemed responsible, citing "reasonable grounds to believe that both the President and the Ministers of People's Power for Interior Relations, Justice and Peace, and for Defence, ordered or contributed to the commission of the crimes documented."

International 'legal action'

World powers accuse Maduro of violently cracking down on dissent over Venezuela's economic collapse and on opponents in a political stand-off.

Investigator Francisco Cox told reporters the team had found evidence the president had on some occasions personally informed the national intelligence service (SEBIN) who to place under surveillance and detain.

"We have involvement and contribution to the crime by Mr. Maduro, either directly through the chain of command and sometimes circumventing the chain of command and giving the direct order," he said.

"What we have reasonable grounds to believe is that this is a state policy... It is a political decision to target political opposition, to quash opposition."

The investigators said Venezuelan authorities should conduct "independent, impartial and transparent investigations" into the violations.

But they noted "an erosion of judicial independence", and suggested the International Criminal Court "should also consider legal actions against individuals responsible for violations and crimes."

The report decried a vast array of abuses committed amid a gradual breakdown of democratic institutions and the rule of law.

It highlighted soaring numbers of extrajudicial killings, lamenting that the vast majority of such killings by security forces had resulted in no prosecutions.

The mission reviewed some 2,500 incidents since 2014 that led to more than 5,000 killings by security forces.

It probed 140 so-called Operations for People's Liberation, established purportedly to fight crime, but which between 2015 and 2017 resulted in 413 people being killed, shot "sometimes at point blank range".

The report said government officials had repeatedly praised such operations.

'Systematic' torture 

"These extrajudicial executions cannot be attributed to a lack of discipline among the security forces," Valinas said.

"The killings appear part of a policy to eliminate unwanted members of society under the cover of combating crime." 

The investigators called for Venezuela to dismantle its Special Action Forces (FAES), which along with SEBIN was responsible for well over half of the killings.

UN rights chief Michelle Bachelet had called last year for the forces to be dissolved, but Valinas said they were "still active".

The investigators also decried the "systematic practice of torture" against people detained during anti-government protests or accused of rebellion and coup attempts.

It listed techniques including rape, asphyxiation, beatings, electric shocks and death threats to extract confessions or as punishment.

At least three people had died after being subjected to torture while in the custody.

Cox stressed that commanding officers and high-level officials "had full knowledge of this pattern of crimes".

He said the investigators had drawn up a list of 45 officials within the two agencies "who should be investigated and prosecuted".