Pakistani troops battle Taliban in key Swat Valley city

At least 17 Taliban fighters were killed Saturday after Pakistani security forces moved into the main city in the Swat Valley and engaged in fierce street battles, say military officials.

Capturing Mingora is critical to government efforts to regain the valley in the north of Pakistan and prevent it from being a safe haven for insurgents, who are said to threaten the country's stability.

Thousands of civilians began fleeing Mingora last week ahead of the troop advance, but between 10,000 and 20,000 remain, according to army spokesman Maj.-Gen. Athar Abbas. Its normal population is about 375,000.

"The terrorists are going to use them as human shields. They are going to make them hostage, so we are moving very carefully," Abbas said. "The pace of the operation will be painfully slow."

The military said around 1,100 suspected insurgents have died so far in the month-old offensive. It has not given any tally of civilian deaths, and it's unclear how it is separating regular citizens killed from militants. Residents fleeing the region have reported dozens of ordinary Pakistanis killed in the fight.

Abbas said as many as 2,000 insurgents remain in the valley.

It's believed the fighting has displaced as many as 1.7 million people in the Swat Valley since early May.