The U.S. military reserves the right to cross the border into Pakistan in hot pursuit of enemy fighters who may flee there from Afghanistan, a U.S. military spokesman said Friday.

Pakistani Foreign Ministry spokesman Aziz Ahmad Khan said his country was looking into the American military's statement, but had no immediate comment.

"We are in the process of verifying if the statement was really made and at what level," he told The Associated Press in Islamabad.

U.S. military spokesman Maj. Stephen Clutter said Friday the policy of hot pursuit had been a long-standing one. It appears, however, to be the first time it has been made public.

Until now, U.S. officials have vehemently denied crossing the Pakistani border to pursue fleeing Al Qaeda or Taliban suspects.

"It is a long-standing policy that if we are pursuing enemy forces, we're not just going to tiptoe and stop right at the border," Clutter said at Bagram Air Base, the U.S. military headquarters in Afghanistan.

"We do reserve the right to go after them and pursue them and that is something that Pakistan is aware of ... In hot pursuit, we're going to chase down the bad guys."

Clutter said, however, that U.S. forces had not yet crossed into Pakistan in any hot pursuit operation. He said the closest they had come was during an incident on the Afghan side of the border on Sunday in which a Pakistani border guard shot a U.S. soldier in the head.

U.S. and Pakistani officials have played down the hot pursuit policy for fear it would inflame anti-American Islamic militants in Pakistan.

The last time it was mentioned publicly was in March 2002, when U.S. Maj. Gen. Frank Hagenbeck, then commander of U.S. forces in Afghanistan, said American troops might chase Al Qaeda fighters into Pakistan in hot pursuit.

At the same time, U.S. Deputy Defense Secretary Paul Wolfowitz said "that's a possibility" but stressed such action would come under limited circumstances and with Pakistani consultation.

Another U.S. spokeswoman, Master Sgt. Kelly Tyler, said the U.S. military's official rules of engagement had not changed but were not generally publicized "as it can become a security issue and endanger the lives of our soldiers."

"U.S. forces have always retained the right to defend ourselves from hostile actions. If it is necessary to pursue the enemy in that defense, then that is what will happen," Tyler said. "We retain the right and the obligation to protect our soldiers by any means necessary."

The news comes amid growing anti-American sentiment in Pakistan, where Pakistani security agencies were bracing Friday for planned nationwide protests against a possible U.S.-led war on Iraq.

On Sunday, a rogue Pakistani border guard shot and wounded an American soldier in the head in troubled eastern Afghanistan's Paktika province, just a few hundred yards from the Pakistan border.

The shooting prompted American forces to call in an airstrike on a building where the Pakistani border guard was believed to be hiding. The military says the building was also in Afghanistan, but the Pakistani government says it is investigating. U.S. forces said Thursday the Pakistani border guard had been detained by authorities in Pakistan.

"It is important to reiterate that personnel on either side of the border should not approach coalition forces engaged in the conduct of their mission, as they place themselves in danger," Tyler said.

Sunday's incident prompted hard-line Islamic groups in Pakistan on Thursday to call for the United States to pull its troops out of the region, saying the clash exposed the dangers of the American presence.

Many hard-line politicians in northwestern Pakistan have long been outraged over Pakistan President Gen. Pervez Musharraf's decision to join the U.S.-led campaign to overthrow Afghanistan's Taliban rulers following the Sept. 11 terrorist attacks last year.