Pro-Taleban militants have attacked a check post in north-west Pakistan and abducted 12 soldiers, officials say.
Scores of soldiers have been kidnapped in recent days
The militants, armed with rocket launchers and heavy weapons, attacked the troops outside the town of Bannu near the North Waziristan tribal area.
The rebels are still holding scores of soldiers they kidnapped a fortnight ago in nearby South Waziristan.
Violence has soared since troops were sent in to oust radical Islamists from Islamabad's Red Mosque in July.
More than 100 people died in the operation.
The latest fighting coincided with a visit to Pakistan by the American deputy secretary of state, John Negroponte.
The United States is pressing Pakistan to take stronger action against Taleban and al-Qaeda miliants operating from its border areas.
Spate of kidnappings
"After the rocket attack, about 200 militants launched a physical attack on the post and kidnapped 12 men of the Frontier Constabulary," Reuters news agency quoted an officer in the force, Amir Badshah Utmankheil, as saying.
He described the attackers as "local Taleban".
Later in the day, the military said army helicopters and artillery had bombarded militant positions in North Waziristan. Up to 40 militants had been killed, a spokesman said.
There was no independent confirmation of the report. Local officials told the BBC they had no knowledge of any clashes.
The latest kidnapping comes amid negotiations to free the soldiers abducted two weeks ago. The insurgents say they are holding about 300 troops.
Local tribal elders have been negotiating with the rebels to secure the men's passage to safety after they went missing in the Ladha area of South Waziristan on 30 August.
Last week, the rebels released six of them in what they called was a "goodwill gesture".
The militants have demanded the release of a number of prisoners and an end to military deployment in their area.
There has been a spate of kidnappings in the tribal areas in the recent weeks.
Last month, militants freed 18 soldiers, but only after they had beheaded one and videotaped the killing.
The army has given conflicting accounts of what happened to the soldiers in Ladha on 30 August.
First they said the men had been caught in bad weather and had taken shelter.
Then they said no troops had been seized, but that about 180 men were stuck in fighting between militants and tribesmen and unable to leave.
Correspondents say that the kidnapping of so many soldiers, apparently without a fight, has been a major embarrassment for the authorities.