Twenty-five foreign fighters were killed and wounded by Afghan security forces after they crossed the border from Pakistan, a government official said, the first sign of retaliatory attacks in Afghanistan after al Qaeda leader Osama bin Laden was killed.
Bin Laden, the architect of the September 11, 2001, attacks on the United States, was killed by U.S. forces in a dramatic raid north of the Pakistani capital, Islamabad, Monday, sparking fears of revenge by Islamist militants, reports Reuters.
Jamaluddin Badr, governor of north-eastern Nuristan province, said the 25 foreign fighters killed and wounded overnight included Arabs, Chechens and Pakistanis. He said the operation was launched to guard against attacks after bin Laden's death.
"We are aware of the situation here now that al Qaeda and other elements will try to infiltrate into Afghanistan. We have launched an operation to control border infiltration," Badr told Reuters.
Tuesday's operation was in the Barg-e-Matal district of Nuristan, very close to the border with Pakistan, Badr said.
Taliban, al Qaeda and other Islamist militants have long operated out of safe havens and training camps in Pakistan's largely lawless northwest Pashtun tribal regions.
Bin Laden was sheltered by the Afghan Taliban before the September 11 attacks and managed to escape U.S. troops and Afghan militia during an assault in Afghanistan's mountainous Tora Bora region before slipping across the border into Pakistan.
Military commanders, political leaders and analysts have warned that the immediate effect of bin Laden's killing for Afghanistan would likely be a spike in violence as Islamist militants seek to strike back.
"I don't think the death of bin Laden will directly impact the fighting capabilities of any of the parties engaged in the war in Afghanistan," Martine van Bijlert of the Afghanistan Analysts Network wrote in a blog (www.aan-afghanistan.com).
"I guess the Taliban are now trying to figure out how to position themselves. They will want to use the mobilising potential of bin Laden's death, but they will also want to leave their position vis-a-vis al Qaeda sufficiently ambiguous to keep future options open," she said.
The Afghan Taliban have so far not commented on bin Laden's death. Their counterparts in Pakistan have vowed to step up attacks against Pakistani and U.S. targets.
Mullah Abdul Salam Zaeef, the former Taliban envoy to Pakistan, said the United States had achieved their purpose in killing bin Laden and should now leave Afghanistan.
"If it's real, there is no necessity for the Americans to do operations in Afghanistan anymore," Zaeef told Al Jazeera television.
Even before bin Laden's killing, senior NATO commanders warned a big wave of violence was expected this week and the Afghan Taliban had announced it would begin a new wave of violence as part of the spring fighting season.
Fighting traditionally picks up in Afghanistan when winter snow melts allowing militants to move through the mountains.
U.S.officials have also sought to make clear that there would be no immediate change in U.S. policy in Afghanistan.
Washingtonis committed to beginning a gradual drawdown of its combat troops in Afghanistan from July, a process that will culminate with Afghan security forces taking over from foreign forces by the end of 2014.
Violence across Afghanistan hit its worst levels in 2010 despite the presence of 150,000 foreign troops, with civilian and military casualties hitting record highs.