Heavily armed militants tried to storm Pakistan's army headquarters Saturday, with six soldiers and four rebels killed in the audacious attack near the capital Islamabad, officials said.

Six insurgents armed with automatic weapons and grenades drove up to the compound and shot their way through one checkpost in the garrison town of Rawalpindi, before being stopped by security forces at a second post.

Two militants managed to flee during the fierce firefight, and were still on the run despite helicopter gunships circling overhead and commandos manning a security perimeter around the military headquarters, army officials said.

The attack comes amid a surge in insurgent strikes, as analysts say the Islamist Taliban militia try to deter an army offensive into their tribal stronghold along the mountainous border with Afghanistan.

Army spokesman Major General Athar Abbas said the militants were dressed in army uniform and "were armed with sophisticated weapons and grenades."

"They came in a van and tried to enter from gate one to gate two in the sensitive area. They were stopped and now the situation is under our control," he said in an interview on private TV channel Geo.

His deputy Colonel Attique ur Rehman told AFP: "Six soldiers were martyred in the attack." The dead are reported to include a senior army officer.

The firefight came a day after a devastating suicide car bomb killed 52 civilians at a busy market in the northwest city of Peshawar.

Government ministers blamed the Taliban, who have also vowed to avenge the death of their leader Baitullah Mehsud in a US drone missile attack in August.

Another military official in Islamabad said there were at least six attackers in the assault on the heavily fortified army command centre.

"Four were killed. Two are still missing. The hunt is going on," said the official with Pakistan army's media wing.

He blamed the attack on Tehreek-e-Taliban Pakistan (TTP), the umbrella militant movement based in the semi-autonomous tribal belt and blamed for most the attacks which have killed more than 2200 people here in two years.

An AFP journalist at the scene of Saturday's gunbattle reported that the firefight began just before midday and lasted about an hour and a half, with helicopters ferrying the dead militants away after the battle ended.

Witnesses said that the militants hurled hand grenades, with one man saying five explosions rang out amid the gunfire.

"A car was signalled to stop outside army headquarters," local police officer on the scene Amjad Ali told AFP. "The occupants opened fire and threw grenades at security guards who retaliated."

Prime Minister Yousuf Raza Gilani strongly condemned the attack, a brief statement issued by his office in Islamabad said, and met the army chief and president to discuss the security situation.

Police officials said that security had been beefed up in the capital Islamabad, amid fears of more insurgent strikes.

The military is wrapping up a fierce offensive against Taliban rebels in the northwestern Swat valley launched in April, with the army now poised to begin a similar assault in the lawless tribal belt.

Taliban and Al-Qaeda rebels who fled Afghanistan after the 2001 US-led invasion have carved out boltholes and training camps in the remote Pakistani mountains, with the TTP leadership also holed up in the rugged terrain.

Several bomb blasts in Pakistan in the past two and a half weeks have killed dozens, with the Taliban threatening to unleash bigger assaults.

The TTP have already claimed responsibility for a suicide attack on Monday on a UN office in Islamabad, which killed five aid workers.

There was a lull in bomb attacks after Baitullah Mehsud's death in an August 5 US drone strike, but analysts had warned that the new Taliban leadership would likely be keen to show their strength with fresh, dramatic strikes.

Interior Minister Rehman Malik said after Friday's Peshawar bombing that the the attack could force the military to bring forward a planned operation to wipe out Islamist militant strongholds in the tribal region.