KABUL, Afghanistan -- U.S. special forces and Afghan fighters went cave to cave in Tora Bora trying to pick up the trail of Osama bin Laden after his al-Qaida fighters fled the mountainous region.
The Pentagon is considering sending a larger force of Marines to Tora Bora to help the several dozen U.S. special forces searching the caves, a defense official in Washington said on condition of anonymity. The whereabouts of bin Laden, alleged mastermind of the Sept. 11 terrorist attacks in the United States, are unknown.
The first British peacekeepers flew into Afghanistan on Thursday as the United Nations approved their mission to help the nation heal after decades of war. Even as they landed, the Afghan defense minister insisted they would have no authority to use force.
The dangers in the strife-ridden country were brought into sharp focus by an afternoon explosion in the northern city of Mazar-e-Sharif, where a fragmentation grenade ripped through a market, wounding 100 people.
One of the wounded said he saw the grenade roll into the moneychangers' section of the market. The local health minister, Mirwais Rabde Sherzod, called the explosion a "terrorist act."
Fifty-three British Royal Marines landed at Bagram air base north of the capital on Thursday, part of an initial contingent of up to 200 peacekeepers that will move into Kabul ahead of Saturday's inauguration of an interim administration.
The U.N. Security Council unanimously backed the British-led multinational force for the Kabul area. The force, which will eventually number 3,000-5,000 troops, was authorized to take military action as it helps keep security under the interim government, which is to rule for six months.
The head of the incoming government, Hamid Karzai, has welcomed a more powerful role for the international troops. The interim foreign minister, Abdullah, sent a letter to the Security Council last week agreeing to a clause allowing military action, backing off an earlier refusal.
But interim Defense Minister Mohammed Fahim, reflecting an unease over the presence of foreign forces and their involvement in factional feuds, was opposed. He insisted the multinational force will have no authority to disarm belligerents, interfere in Afghan affairs or use force.
"They are here because they want to be. But their presence is as a symbol. The security is the responsibility of Afghans," Fahim said of the peacekeepers. He told The Associated Press: "The peacekeepers can patrol if they want to."
"They have no right to disarm anyone," said Fahim, a leader in the faction that controls Kabul. Some new government ministers returning from exile "feel they need the peacekeepers for protection, but when they arrive here they will see that the situation is OK and that it is not necessary."
The agreement signed by four Afghan factions setting up the interim government authorized the security force, initially in Kabul and its surroundings and possibly elsewhere later on. Its primary role is to provide security for the new government, its buildings, the main airport at Baghram outside the capital, and the appraches to Kabul.
In other developments:
-- Pakistani troops recaptured a dozen al-Qaida fighters from a group of Arabs who had escaped their guards after being captured while trying to flee across the border from Tora Bora. Another of the group was killed along with a soldier in a gunbattle. Officials said up to seven fugitives remained at large.
-- An AP photographer and two photographers working for The New York Times were detained at gunpoint in the Tora Bora area by Afghan tribal fighters after they photographed American special forces soldiers. The tribal fighters confiscated their digital film discs, while U.S. soldiers looked on, the journalists said.
The U.N. decision to authorize peacekeepers to use force was critical for Britain and other countries expected to contribute troops, who had said they would not participate otherwise.
"The United Kingdom is ready to go," said Jeremy Greenstock, Britain's ambassador to the United Nations. The Security Council, he said, has provided "some new hope for what has been a pretty miserable life for Afghans over the last few years."
U.S. Ambassador John Negroponte added: "It was important to send that signal of support for the interim government."
Fahim, however, said the main goal of the force was to reassure foreign donors.
He said the international force will eventually number 3,000 troops, only a third of whom will have a peacekeeping role. The rest will assist with humanitarian aid and serve as a reserve, out of sight at Baghram, Fahim said.
Greenstock said it would be a "unified force," with all troops involved in peacekeeping.
Another difference emerged over the role of the heavily armed units of the northern alliance, which swept into Kabul and drove out the Taliban in November.
Fahim said the forces would withdraw from the streets but would not leave the capital. Many of their barracks are in the heart of the city.
The agreement signed in Germany by the alliance and other Afghan factions on creating the new government mandated that all Afghan military units are to withdraw "from Kabul and other urban centers or other areas in which the U.N.-mandated force is deployed."
Many Afghans want peacekeepers to prevent the groups that make up the northern alliance from returning to the bitter feuding that marked their 1992-96 rule, during which they destroyed entire Kabul neighborhoods and killed 50,000 people, most of them civilians.
That period of turmoil followed years when many Afghans battled Soviet forces during an occupation that began in 1979.