Several international aid agencies removed foreign staff from southern Afghanistan on Thursday while other groups were keeping a low-profile following last week's murder of a Red Cross worker.

Evidence is mounting in the southern regions of Afghanistan that the Taliban is reorganizing and carrying out attacks against U.S. troops and foreigners in the region. Intelligence sources say the Taliban have aligned themselves with rebel renegade leader Gulbuddin Hekmatyar, whose soldiers have attacked and killed foreign civilian workers in Afghanistan during previous conflicts.

Medecins Sans Frontieres (Doctors Without Borders) flew its four international staff members to the western province of Herat, along with several other aid groups who also removed their staff "to safer locations," said John Oerum, the United Nations' southwestern regional security chief.

The United Nations, meanwhile, ordered its staff to stay off the roads for the next two weeks while it rethinks its security plans.

"We are looking at our security with new eyes," Oerum said. "We have kept a low profile for the last 72 hours."

Last week, Red Cross worker Ricardo Munguia of El Salvador was shot 20 times and the vehicles in his convoy were torched. Witnesses said the Taliban warned his Afghan colleagues against working with foreigners.

Government officials here said the killing was an attempt to frighten off aid workers who would rebuild the shattered nation and help bring stability to President Hamid Karzai's government.

The International Committee of the Red Cross, which has 150 foreign workers in the country, has suspended its Afghan operations indefinitely.

On Wednesday, the State Department issued a new travel warning for Afghanistan, saying "the ability of Afghan authorities to maintain order and ensure security is limited."

The warning added that there were numerous causes of concern, including land mines, banditry, armed rivalry among political and tribal groups, and the possibility of terrorist attacks.

"Remnants of the former Taliban regime and the terrorist Al Qaeda network, and other groups hostile to the government, as well as criminal elements, remain active," the warning said.

Oerum said the fighting in Iraq is emboldening the Taliban, whose regime was overthrown in 2001 by a U.S.-led war, adding that "the longer the war drags out the more dangerous it is going to become" for foreigners.