Agnes Callamard, the United Nations special rapporteur on extrajudicial killings, used a policy forum at a Manila university on Friday to issue a veiled criticism of President Rodrigo Duterte's deadly war on drugs.

The envoy has long spoken out about allegations of systematic summary executions in the country, where thousands of suspected drug dealers and users have died since Duterte launched his campaign in mid-2016.

Callamard told the forum she was not in the Philippines in any official capacity and would not be conducting research during her trip, but presidential spokesman Ernesto Abella said the government should have been told about her visit.

Read more: Police in Philippines relaunch crackdown on illegal drugs

"Callamard has arrived in the Philippines in a manner that circumvents all recognized United Nations protocols for such visits," he said.

"We are disappointed that, in not contacting our government in advance of this visit, she has sent a clear signal that she is not interested in getting an objective perspective," Abella said in a statement.

UN investigation

The UN and the Philippines have differing accounts of Callamard's request to investigate allegations of extrajudicial drugs-related executions in the country.

The envoy sought to visit the Philippines last year, but said she ultimately couldn't accept the government's condition that she publicly debate Duterte. Instead, she had suggested a joint news conference.

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Spokesman Abella said she had failed to respond when the government in September formally invited her to visit, which he said suggested she "would not be approaching her review of allegations concerning our country objectively or comprehensively."

War on drugs 'not working'

In her speech at the university Friday, Callamard did not mention the Philippines by name, but said world leaders had recognized that "badly thought out, ill-conceived drug policies” not only fail to address drug abuse and trafficking but they add more problems to society. She added that UN member countries instead favored a multi-faceted and scientific approach that promotes the human rights of individuals and communities.

She later told reporters she had no ulterior motive for visiting the Philippines, and was there only "for the purpose of an academic conference."

Activists in the Philippines allege police are behind thousands of drug user murders, but authorities deny extra-judicial killings have taken place. They say police are only responsible for deaths that were in self-defense during anti-drugs operations.

nm/rt (AP, Reuters)