Militants hold hostages at army HQ

Six soldiers, including two ranking officers, and four militants were killed in the attack by assailants who wore military uniforms.

The strike appeared to be a warning to the military that its planned offensive on the insurgents' stronghold along the Afghan border would be met with attacks against targets across Pakistan.

The government said the assault on the headquarters, which followed a bloody market bombing and a suicide blast at a UN aid agency in the past week, had strengthened its resolve to push into South Waziristan - a mountainous region home to al Qaida leaders where security forces have been beaten back by insurgents before.

The surge of violence was confirmation that the militants had regrouped despite recent military operations against their forces and the killing of Pakistani Taliban leader Baitullah Mehsud in a CIA drone attack in August.

His replacement vowed just last week to step up attacks around the country and repel any push into Waziristan.

Army spokesman Major General Athar Abbas said "four or five" attackers were holding between 10 and 15 troops hostage in a building close to the main gates of the complex in Rawalpindi, a city near the capital, Islamabad. No senior military or intelligence officials were among those being held, he said.

Maj Gen Abbas said special forces had surrounded the building.

"They will decide how and when to act," he said, declining to comment on whether authorities had attempted to talk to the hostage-takers or whether they had made any demands.

No group claimed responsibility, but authorities were sure that the Pakistani Taliban or an allied Islamist militant group were behind it.