Authorities launched an investigation Wednesday into the killings by Afghan security forces of at least 15 people who an Afghan army commander alleged were Taliban rebels but locals said were tribesmen wanting to attend a religious festival.

The bodies were found near the border town of Spin Boldak in Kandahar province, where some 2,000 members of the Noorzai tribe protested the slayings and demanded action be taken against Afghan forces responsible.

Kandahar provincial Gov. Haji Asadullah Khalid said he did not know whether the victims were Taliban fighters who had crossed into Afghanistan from neighboring Pakistan, but he sent a team to investigate.

"We are trying to learn if this is an issue involving the Taliban or if it was a criminal matter," Khalid said at a news conference in Kandahar. "If it is a criminal issue, we will try those responsible in court."

Earlier in the day, frontier security commander Abdul Razzak said his forces had fought a two-hour gun battle late Tuesday against a group of suspected Taliban rebels.

He said the victims included 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 frontier.

But Khalid's deputy and a member of the Noorzai tribe, Naimat Khan Noorzai, rejected claims that those killed were Taliban fighters, saying "they were killed in cold blood because of a tribal conflict" allegedly involving Razzak's tribe.

Neither Razzak nor other members of his tribe were immediately available to comment on the allegations.

Noorzai said the victims were planning to travel from the capital, Kabul, to the northern city of Mazar-e-Sharif to celebrate Nowruz, an ancient Persian spring festival that marks the new year in Afghanistan. It is a predominantly Shiite Muslim event, but it's also celebrated by Sunnis.

The fighting was the deadliest in weeks in Afghanistan and may further aggravate 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.

Violence on both sides of the largely mountainous frontier, where Usama 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 has more than 18,000 troops in Afghanistan more than four years after the Taliban was driven from power.

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