Militants armed with guns and rocket launchers stormed a Pakistani air force base before dawn on Thursday, sparking heavy clashes that left eight people dead, officials said.

Two security officials were killed at PAF Base Minhas in Kamra, where suspected Islamists again penetrated a sensitive military site in the nuclear-armed country, which has been battling a Taliban insurgency for five years.

The attack comes amid speculation that Pakistan could launch an operation against militants in the tribal district of North Waziristan, where Washington has long demanded an offensive against the Al-Qaeda-linked Haqqani network.

The Air Force said six to seven attackers armed with rocket propelled-grenades and automatic weapons attacked the Kamra base, home to to the Pakistan Aeronautical Complex that assembles Mirage and JF-17 fighter jets, at 2:00 am (2100 GMT Wednesday).

"Other miscreants then fired RPGs from outside the base boundary wall. As a result one PAF aircraft got damaged," the air force said in a statement.

That gunmen got inside the facility at all just 60 kilometres (37 miles) northwest of Islamabad will renew questions about poor security, particularly at a base which has been attacked twice before.

Gunfire, rocket and hand grenade explosions could be heard during what were described as heavy clashes. One officer told AFP that he saw flames after waking up for his late night meal, eaten during the dawn-to-dusk Muslim fasting month of Ramadan.

"There was an announcement by megaphone for soldiers not to move from the barracks and we were forbidden from going to the area where I saw the fire," he said.

Special forces were scrambled to the scene.

The Air Force said six attackers strapped with suicide jackets and two security personnel were killed in a shootout that lasted "for more than two hours".

The base commander was also wounded and forces were searching the rest of the base to ensure no other gunmen remained, the military said.

An AFP reporter who arrived at the base after daybreak said it was quiet.

There was no immediate claim of responsibility but the Pakistani Taliban have targeted a string of military bases since rising up against the government in July 2007.

In May 2011, it took 17 hours to quell an attack on an air base in Karachi claimed by the Taliban, piling embarrassment on the armed forces just three weeks after US troops killed Osama bin Laden in Pakistan.

Thursday's attack was the second in weeks to see troops die near the relatively secure capital. Gunmen on July 9 killed seven security personnel who had camped by a river less than 160 kilometres (100 miles) southeast of Islamabad.

Despite a relative lull in high-profile attacks, Pakistan has been on alert for violence to coincide with its independence day on Tuesday this week and the Muslim festival of Eid, which is expected to begin at the weekend.

On Tuesday, the head of the army, General Ashraf Kayani, used his independence day address to describe the war on terror, often seen in Pakistan as an American battle, as "our own war and a just war too".

He acknowledged the difficulties of fighting his own people, but said "no state can afford a parallel system of governance and militias," and called on the nation to stand united or face the risk of a "civil war situation".

Pakistan says 35,000 of its people, including more than 3,000 soldiers, have been killed as a result of terrorism since the 9/11 attacks and the 2001 US-led invasion of neighbouring Afghanistan.

The base in Kamra was previously targeted on October 23, 2009 when a suicide bomber killed six civilians and two Pakistan Air Force personnel at a checkpoint.

On December 10, 2007, a suicide car bomber struck a school bus, wounding at least five children of base employees.