Officials in Afghanistan say suspected Taliban insurgents have killed three female international workers of a U.S aid organization and their Afghan driver.  Ayaz Gul gives more details from Islamabad.

Afghan women walk past coffins containing the bodies of three foreign aid workers in a hospital in Pul-e-Alam in Logar province, Afghanistan, Wednesday, 13 Aug. 2008

The killing took place in the Afghan province of Logar and is being described as the bloodiest single attack on foreign humanitarian workers in Afghanistan in recent years. 

Police say the three female foreigners worked for the New York-based International Rescue Committee and were traveling to Kabul with their Afghan driver when a group of armed men opened fire on their vehicle.

Security officials have recovered the bodies of the four victims and Interior Ministry spokesman Zamary Bashari says police have launched an investigation. 

"This attack was conducted by unknown armed men. The police of Logar are investigating the case very seriously and we are trying to find those who are behind the issue," Bashari said.

The U.S.-based aid agency provides emergency relief to returning refugees and helps rebuild water and sanitation as well as the health care system in Afghanistan. 

International aid agencies say that attacks on their workers in Afghanistan have gone up this year, killing at least 19 local aid workers.

They have complained that the violence has already forced humanitarian groups to restrict their activities and Wednesday's attack will further undermine their work at a time when drought and rising food prices are putting more Afghans under pressure.

The security situation has deteriorated in parts of Afghanistan and the commander of international security forces has reported a 50 percent increase in insurgent attacks across the country this year.