A brazen attack by hundreds of Taliban militants on an isolated town had been building for days, a coalition spokesman said Friday, after a wave of violence in southern Afghanistan left around 100 dead.

The attack Wednesday night on Musa Qala in the volatile southern province of Helmand sparked eight hours of fighting and left about 40 Taliban and 13 Afghan police dead.

It was the epicenter of some of the fiercest combat since the Taliban regime's ouster by U.S.-led forces in late 2001 and raised new fears about deteriorating security in the hardline militia's former southern heartland.

In all, more than 100 people were reported killed in a string of attacks and engagements across Afghanistan that started Wednesday and continued through Thursday: up to 87 insurgents, at least 15 Afghan police, an American civilian training Afghan forces, and the first female Canadian soldier to die in combat.

CountryWatch: Afghanistan

NATO Secretary-General Jaap de Hoop Scheffer said the mission in Afghanistan will not be deterred by a recent surge in violence there, and opponents of nation-building will be defeated, the head of the alliance said Friday.

"NATO will stay the course and the spoilers will not have a chance," the alliance's chief said during a visit to Lisbon. "The operational plan is robust and the rules of engagement are robust."

Thousands of NATO troops, including forces from Canada, Britain and the Netherlands, will be stationed in areas where attacks have occurred.

"We will go in very robustly on the basis of robust rules of engagement," de Hoop Scheffer said.

"We will not accept that the spoilers — the Taliban, the Al Qaeda — will be able to spoil this process of Afghanistan in its democratic development."

There were no reports of further violence Friday.

Coalition forces had reports from Musa Qala on Tuesday that the Taliban or criminal elements were trying to infiltrate the village.

"Then the whole thing blew up" on Wednesday and Thursday, said Maj. Quentin Innis, a coalition spokesman based in Kandahar.

Innis said the Taliban often infiltrates villages and extorts money from tribal elders, but that leaders in Musa Qala had told the militants they weren't welcome. The militants then mounted their attack using machine guns and assault rifles.

Innis said coalition forces flew military aircraft overhead to scare the Taliban militants and as a show of force, but that the Afghan police forces did 100 percent of the fighting in the eight-hour clash.

"We see this as them taking control of the situation and sorting it out for themselves," he said. "We see it as very empowering on their part, and of course that's what we want, because eventually we're going to leave."

The fighting on Wednesday and Thursday was concentrated in the southern provinces of Helmand and Kandahar, the scene of repeated bombings and suicide attacks this year. But it marked an escalation in a region where the U.S.-led coalition is to cede control of security operations to NATO by July.

NATO plans to deploy thousands of extra troops from nations including Canada, Britain and the Netherlands to take control of security operations from the U.S.-led coalition, which has been hunting for Taliban and Al Qaeda militants in the south since late 2001.

By the end of this year, NATO will also assume command in the volatile eastern region of Afghanistan, where U.S. forces will continue to operate but under the military alliance.

President Hamid Karzai on Thursday said the violence emanated from the mountainous border regions of neighboring Pakistan, populated by the ethnic Pashtuns who make up the majority of the Taliban militants. It's also a likely hiding place of Usama bin Laden.

Pakistan's Interior Minister Aftab Khan Sherpao late Thursday rejected Karzai's comments, saying that "we were saddened by such statement."

"Afghanistan will not benefit by such statements. They will breed ill will," Sherpao said.