A UN rights official has alleged that foreign intelligence agents have taken part in secret raids in Afghanistan that have killed civilians.

UN special rapporteur Philip Alston told reporters Thursday in Kabul that he is 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 said one raid in January that killed two Afghan brothers was conducted by Afghans and personnel from a U.S. special forces base in Kandahar.

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

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