MIRANSHAH: US missile strikes killed at least seven militants in northwest Pakistan on Wednesday, as attackers armed with rockets and petrol bombs killed five policemen in a pre-dawn ambush.

US drone attacks target Taliban and Al-Qaeda-linked commanders in the nuclear-armed country's northwest tribal belt, where militant networks have carved out havens in lawless mountains outside direct government control.

Two US missile strikes killed seven militants in North Waziristan, which is infested with multiple militant factions and increasingly the focus of the US drone war against Al-Qaeda and Taliban fighters active in nearby Afghanistan.

The first attack struck Hamzoni, a village in North Waziristan, where five missiles slammed into two vehicles at around 7:15 am (0215 GMT), a senior Pakistani security official told AFP.

"Five militants were killed in the missile strike," the official said.

The second attack took place in Myzer Madhakhel, another village in North Waziristan, at around 8:00 am (0300 GMT). At least two militants travelling in a pick-up truck were killed, the official said.

The exact identity of the militants was unclear and it was not immediately known whether they included any high-value targets, but other security officials confirmed the same death toll.

Washington calls Pakistan's semi-autonomous tribal belt the global headquarters of Al-Qaeda and the most dangerous region on Earth, where Islamist militants are fuelling the more than eight-year war in Afghanistan.

North Waziristan's prominence in the covert US drone war has grown since a suicide attack killed seven CIA employees in a neighbouring Afghan province last December.

On Tuesday, another drone attack destroyed a mountain hideout in North Waziristan, killing 10 militants, including Al-Qaeda-linked suspects, although no high-profile targets were listed as dead.

On the ground in Afghanistan, Washington is spearheading a build-up of 150,000 foreign troops this year as part of a new counter-insurgency strategy designed to beat back the Taliban and restore Afghan government authority.

Under US pressure, Pakistan's military claims to have made big gains against Taliban and Al-Qaeda strongholds over the past year, following major offensives in the northwestern district of Swat and in South Waziristan.

Suspected Islamist militants armed with rockets and petrol bombs ambushed a security checkpoint at Speen Qabar near the Khyber tribal district before dawn on Wednesday, killing five policemen, officials said.

Dozens of militants lobbed rockets at the checkpoint, then opened fire with automatic weapons before throwing petrol bombs, setting it on fire, senior police official Mohammad Karim Khan told AFP.

"Three Frontier Constabulary personnel and two policemen were martyred in the attack and the sixth policeman posted (at the checkpoint) is the lone survivor, but he is also wounded," Khan said.

He blamed the attack on Lashkar-e-Islam, a Pakistani Islamist group with ties to the Taliban that has long stirred up trouble in Khyber.

Elsewhere in Khyber, militants stuck a bomb under a tanker carrying fuel for NATO forces in Afghanistan. The vehicle exploded into a huge ball of flames, administration official Shafirullah Wazir said.

"The bomb was fixed to the tail end of the tanker with a magnet and the explosion burnt some 40,000 litres (8,800 gallons) of fuel it was carrying for NATO forces in Afghanistan," Wazir told AFP.

Another Khyber official, who blamed the tanker attack on Lashkar-e-Islam, said there were no casualties.

The bulk of supplies destined for foreign troops across the border in Afghanistan are driven through Khyber, making the region a logistical bottleneck and prime target for militants.