The Pakistani army says it has seized parts of the Swat valley, as it begins the second day of an offensive against Taliban militants in the main city.
Troops are engaged in hand-to-hand fighting with the militants in Mingora, and are said to have cleared them from another town, Matta.
At least 17 militants have been killed in the clashes, the army says. The Taliban deny the deaths.
The fighting began after a peace deal broke down earlier this month.