By Chris Morris
BBC News, Islamabad
Pakistani troops have begun a major ground offensive against pro-Taleban militants in a former tourist resort in the North West Frontier province.
Military officials say more than 200 militants have been killed in the past week, but there is no independent confirmation of those figures.
A curfew has been imposed in the area around the Swat Valley, about 160km (100 miles) from Islamabad.
Thousands of civilians are reported to have fled from the fighting.
Food supplies cut
This is the first time that Pakistani ground troops have been in action against militants in the Swat Valley.
For several days helicopter gunships and artillery have been used against pro-Taleban forces who have seized a series of small towns and villages.
Now ground troops are involved, trying to take back territory from militants who have infiltrated the valley from tribal areas along the Afghan border.
A military spokesman says the army has already taken control of a number of mountain peaks.
Food supplies to militant-held villages have also been cut.
The fighting in Swat is highly significant because it is the first major pro-Taleban threat in Pakistan in what is known as a settled area.
Authorities say they have set up a number of tent villages to look after the displaced civilians who have fled from the fighting.
The Pakistani President, Gen Pervez Musharraf, cited the strength of Islamist militancy as one of the main reasons he imposed emergency rule more than three weeks ago.
But the military says the emergency has made no difference to its ability to carry out operations against any insurgent threat.