The United Nations has condemned the killing Saturday of four Afghan aid workers in an ambush in Western Afghanistan. Members of the former Taleban government are being blamed for the attack.

U.N. spokesman Manoel de Almeida e Silva told reporters in Kabul that the victims were traveling in the western Farah province when suspected Taleban gunmen attacked their vehicles. He says the men were employees of the U.N.-sponsored Organization for Mine Clearance and Afghan Rehabilitation.

The spokesman said the United Nations special representative for Afghanistan, Jean Arnaud, has expressed his shock and outrage at the brutal and cold-blooded murder of the four aid workers.

"The cowardly act committed against them cannot be tolerated," said Mr. de Almeida e Silva. "The special representative calls on the authorities to investigate and bring to justice those who seek to destroy the hard-earned peace and cowardly wage war on decent and innocent people."

The deaths of the four aid workers followed several days of violence in southeastern parts of Afghanistan that killed three people, including an American soldier of the U.S. led multi-national anti-terrorism force.

The ousted Taleban government and its allies are believed to be waging a low-level guerilla war against the U.S. backed Afghanistan government of President Hamid Karzai. These rebels have targeted foreign and local troops, as well as aid workers in Afghanistan.