Afghan security forces attacked a group of suspected Taliban rebels after they crossed the border from neighboring Pakistan, killing at least 15 of them, an army commander said Wednesday.

Among the dead was a midlevel Taliban commander, Mullah Shien, who for months has allegedly led several cross-border raids from secret bases on the Pakistani side of the border, said Abdul Razak, the frontier security commander. Shien's followers would regularly attack foreign and Afghan troops and bomb trucks hauling gasoline for the U.S.-led coalition, he said.

"We got a tip-off about them coming across the border. We went down there and fought them," Razak said. "We now have all the dead bodies."

Four insurgents fled back across the Pakistani border after the two-hour gunbattle late Tuesday near the border town of Spin Boldak in Kandahar province, Razak said.

The fighting was the deadliest in weeks in Afghanistan and may further inflame a dispute between Kabul and Islamabad about militants sneaking back and forth across the two countries' 1,470-mile border, most of which is unmarked and unguarded.

Pakistani officials were not immediately available to comment.

Afghanistan has long demanded that Pakistan do more to crack down on militants based on its side. Islamabad has repeatedly said it's doing all it can, pointing to the 80,000 Pakistani troops in the region.

Earlier this month, Pakistani officials claimed that insurgents were in fact moving in the other direction, joining tribal fighting in Pakistan's North Waziristan region.

Violence on both sides of the largely mountainous frontier, where Osama bin Laden is suspected to be hiding, has spiked and much of it has been blamed on the Taliban. The fighting has become a concern for the United States, which maintains about 22,000 troops in Afghanistan more than four years after the Taliban was driven from power.

President Bush and two top US commanders raised the issue in visits to Islamabad this month.