MANILA (Reuters) - The Philippines has canceled a trip next year by the U.N. special rapporteur on extrajudicial killings to look into the rising death toll in its war on drugs, the country’s foreign minister said on Wednesday.

Perfecto Yasay said the United Nations could not pursue its investigation because special rapporteur Agnes Callamard had declined to accept the conditions set by the government of President Rodrigo Duterte.

“They cannot come,” Yasay told reporters in the Cambodian capital of Phnom Penh. “If they will not comply with the conditions of our president regarding their visit to the Philippines to validate their claims, then the trip will not push through. They cannot come here.”

Yasay said there were no indications Callamard would comply with Duterte’s guidelines. He did not say what the government’s guidelines were, although Duterte has said he wanted to challenge the U.N. rapporteur to a public debate.

Since Duterte took office on July 1, police say more than 2,000 people have died in anti-narcotics police operations, with another 3,000 deaths, caused by motorcycle-riding masked men and by vigilante groups, under investigation.

Last month, Callamard wrote to the government, welcoming the Philippines’ invitation to examine situations of extrajudicial, summary and arbitrary executions due to the war on drugs. She had intended to visit during the first quarter of next year.

Yasay said the government must be given the opportunity to question the rapporteurs because the Philippines had already been maligned by allegations of extrajudicial killings.

In its October letter inviting the U.N. rapporteur, the government said it was “entitled to know the motive for the investigation, and why the focus is on the Philippines, when there are other nations responsible for the death of innocent and defenceless individuals elsewhere in the world”.

Duterte has lashed out at U.S. President Barack Obama, the European Union and former U.N. secretary-general Ban Ki-moon for criticizing the government’s anti-drug campaign.