A U.N. rights official alleged Thursday that foreign intelligence agents were acting with impunity in Afghanistan and have taken part in secret raids that have killed civilians.

U.N. envoy Philip Alston said he was aware of at least three such recent raids in the country's south and east. He said no one was taking responsibility for the killings.

He did not name a particular country, but mentioned one raid in January that allegedly killed two Afghan brothers that was conducted by Afghans and personnel from a U.S. special forces base in Kandahar.

He said Afghan government officials have said the victims had no connection to Taliban insurgents.

"It is absolutely unacceptable for heavily armed internationals accompanied by heavily armed Afghan forces to be wandering around conducting dangerous raids that too often result in killings without anyone taking responsibility for them," Alston told reporters.

Alston is a special rapporteur of the U.N. Human Rights Council on extrajudicial, summary and arbitrary executions. He has spent 12 days traveling Afghanistan.

He said foreign intelligence agencies were operating with apparent "impunity" in certain provinces. He said such secret operations were "absolutely unacceptable."

"Based on my discussions, there is no reason to doubt that at least some of these units are led by personnel belonging to international intelligence services," he said.

"I am trying to encourage both the Americans and the Afghan government and others to take some of this seriously," Alston said.

U.S. military officials could not immediately be reached for comment.

Alston said there had also been raids in the eastern province of Nangarhar _ another hotbed of the Taliban insurgency and al-Qaida militants, where U.S. special forces and other American-led units operate. Continued...