The ambush marked another increase in insurgent attacks that have marred efforts to stabilize the southern Asian nation. The suspension affects the organization's staff of 80 foreign employees and 1,400 Afghan employees, Nelke Manders, director of the Dutch branch of Doctors Without Borders, said at a news conference Thursday.
"For the time being, our activities will be suspended nationwide," agency spokeswoman Vicky Hawkins told a news conference. "In the coming weeks we will analyze this event in-depth, but for the moment our priority is to take care of those most affected by this tragedy."
The Nobel Peace Prize-winning organization, known as Medecins Sans Frontieres in French, began pulling all of its foreign workers back to the Afghan capital of Kabul, while leaving local staff in place to perform only emergency activities, MSF spokesman Bas Tielens told the Associated Press.
The assault on the five aid workers on Wednesday in northern Afghanistan's Badghis province marked the deadliest attack on foreign aid workers since the radical Islamic Taliban regime was ousted by U.S.-led coalition forces in late 2001.
Three foreigners -- a Norwegian doctor, a Dutch logistician and the Belgian project coordinator -- and two Afghan staffers were killed when gunmen on a motorcycle fired on their vehicle that bore the organization's red emblem.
Police investigating the incident said a farmer saw two gunmen on a motorbike ambush the workers Wednesday afternoon in a desert area near Khair Khana, a village some 340 miles west of Kabul.
Abdul Hakim Latifi, a purported spokesman for the ousted Taliban regime, called news agencies on Wednesday to say the Taliban militia had carried out the attack.
"We killed them because they worked for the Americans against us using the cover of aid work," Latifi told Reuters in a telephone call. "We will kill more foreign aid workers," he warned.
Provincial police chief Amir Shah Naibzada told The New York Times that he believed Taliban supporters were responsible for the ambush, noting "they have increased their attempts in the area recently."
Meanwhile, fighting escalated on Thursday in a southern Afghan region, where U.S. and Afghan troops, backed by American warplanes, continued to battle a group of suspected Taliban rebels. The fighting occurred in the mountains in the Kandahar province, located some 150 miles from Kabul. Around 300 Afghan troops and a smaller contingent of American soldiers launched the operation late Wednesday night.
A spokesman for the local government said 13 suspected insurgents were killed and eight injured in one of the deadliest conflicts since U.S. troops intensified operations this spring, the AP reported. Two U.S. soldiers and one Afghan were reportedly injured in the fighting.
Also Thursday, suspected Islamic militants lobbed rockets at a U.S. base in southeastern Afghanistan, then fled across the border into Pakistan, U.S. military officers told news agencies.
The continued fighting in the southern part of the nation came less than a week after four American soldiers died in a roadside bombing in the Qalat region. The attack was one of the deadliest against U.S. forces since operations began operations in the area more than two years ago.