KABUL, Afghanistan - The U.S. military on Monday denied that its troops in Afghanistan had made incursions into neighboring Pakistan, which a senior Pakistani official had condemned as "totally unacceptable."

U.S. troops crossing the frontier risked coming under fire from hostile Pakistani tribesmen, Pakistan's Foreign Minister Khurshid Kasuri warned on Sunday.

"Everybody in the tribal area is armed. Supposing there are American casualties on our territory. It will be a very big incident. We don't want that to happen," he said in an interview with CNN.

Pakistan is a key U.S. ally in its hunt for al-Qaida and Taliban fugitives, but it won't allow U.S. troops to operate on its soil. Many inhabitants of it border regions sympathize with Afghanistan's former Taliban regime.

Pakistan has protested to the United States, saying coalition forces crossed into the North Waziristan tribal region on May 5 and May 20. On May 20, American soldiers allegedly searched homes for about three hours before Pakistani officials arrived and told them to leave.

U.S. officials have apologized for the first incident, but deny the second.

Inhabitants reported a third incursion into North Waziristan on May 22, but Pakistan's military said U.S. troops didn't cross on that occasion.

U.S. military spokesman Lt. Col. Tucker Mansager said today there had been no incursions since May 5.

"We have researched these allegations thoroughly and can report without a doubt that coalition forces are conducting operations on the Afghan side of the border only," he said at a press briefing in the Afghan capital, Kabul.

"Pakistan is a valued partner in the global war on terrorism and we respect the sovereign rights of Pakistan as a nation," he said.

Pakistan's military said over the weekend it had called for a meeting with the U.S. military on Tuesday to discuss border incursions.

Foreign Minister Kasuri said that incursions into Pakistan's tribal regions were "totally unacceptable," and would only fuel opposition in Pakistan to supporting the U.S.-led war on terrorism.

Pakistan has deployed 70,000 troops in the tribal areas to block rebels who've used the tribal regions as a sanctuary - possibly including al-Qaida leader Osama bin Laden and his deputy, Ayman al-Zawahri.