The Taleban's insurgency is spreading beyond the Swat Valley
The Pakistan government has sent troops to tackle Taleban militants who have advanced into a region just 100km (67 miles) from the capital, Islamabad.
Officials say the forces will protect government buildings in Buner district, where insurgents have begun patrolling the streets and mounting checkpoints.
As the troops moved into the region, insurgents launched an attack on their convoy, killing at least one soldier.
Meanwhile nine people have been killed in the Khyber region, officials say.
Local tribesmen told the BBC that they were killed by bombs dropped by the Pakistani air force, which was targeting militants in the neighbouring region of Orakzai.
The militants advanced towards Buner from the Swat Valley, a region they largely control.
The BBC's Mark Dummett in Islamabad says if the government is trying to reassert control over the region, its efforts appear to be too little, too late.
The Taleban are reported to have moved several hundred men into Buner from the Swat Valley.
The government sent six platoons - up to 300 men - to deal with the insurgents.
A police official told the BBC that the troops were attacked as they were leaving the village of Totalai in the south of Buner district.
The convoy was heading for Dagar, the central town of the largely mountainous district.
In a separate incident officials confirmed that seven people had died in the Khyber tribal region close to the Afghan border.
The dead were seven children and two women, they said, who died when their homes were bombed - but they did not confirm tribesmen's assertions that the bombs were dropped by the Pakistani air force.
Army officials say 11 militants have been killed so far in an operation in the area which has been continuing for three days. There is no independent confirmation of these claims.
The confrontation in Buner comes just weeks after a peace deal was signed by President Asif Ali Zardari allowing the introduction of Islamic law in Swat.
The deal was designed to end a bloody 18-month conflict with the Taleban in Swat by yielding to some of their demands.
But critics say that the militants can now use Swat as a springboard to take over new areas of the country.
The BBC's Ilyas Khan says many people believe Buner could be the next battlefield for the Pakistani security forces after Swat.
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Human rights group Amnesty International said there was concern that the Taleban were targeting non-governmental organisations, and residents feared the restrictions imposed.
Sam Zarifi, Amnesty's Asia-Pacific director, said: "The people of Buner are now at their mercy, particularly women and girls, whose rights the Taleban systematically deny."
US Secretary of State Hillary Clinton earlier said the insurgency posed a "mortal threat" to world security.
Speaking to a Congress committee, Mrs Clinton said the Pakistani government was "basically abdicating to the Taleban and the extremists".