At least four militants were killed in a US drone attack in Pakistan's northwestern tribal area Friday, hours after a similar strike in the region killed three insurgents, security officials said.

The latest attack targeted a militant compound in Aziz Khen town in Mir Ali district of North Waziristan -- a stronghold of Taliban and Al-Qaeda-linked militants, according to the officials.

"A US drone fired four missiles at a compound killing four militants," one security official said, speaking on condition of anonymity.

"The compound was destroyed and militants have cordoned off the area," he added.

There was no immediate report of any high-value target being killed in the attack.

The United States has significantly escalated its covert drone campaign in Pakistan's lawless northwestern tribal region, amid intelligence claims of a Mumbai-style terror plot to launch commando attacks on European cities.

The Mir Ali area is considered a haven for the Pakistani Taliban, the warlord Hafiz Gul Bahadur, and the Haqqani network, an Afghan group affiliated with Al-Qaeda and considered one of the fiercest foes of the US in eastern Afghanistan.

It is also where five Germans were killed by US missiles on October 4.

Two other intelligence officials confirmed the latest attack and casuality figures. A further security official said six people were killed in the strike.

Aziz Khen is about 25 kilometres (15 miles) east of Miranshah, the main town of the lawless tribal North Waziristan region.

Earlier on Friday US missiles killed at least three militants in the same area, according to Pakistani security officials.

Two missiles were fired at Machi Khel village, around 30 kilometres east of Miranshah.

Local intelligence officials said a vehicle, which was parked inside a compound, and a house were both completely destroyed in the attack.

"At least three militants were killed. The US drone fired two missiles. The target was a vehicle," one of the senior officials told AFP.

A record number of US strikes have killed more than 150 people since September 3 and have raised tensions with Islamabad over reported US criticism of Pakistan's failure so far to launch a ground offensive in North Waziristan.

Prime Minister Yousuf Raza Gilani this week called the drone attacks "counter-productive".

The United States does not as a rule confirm drone attacks, but its military and the Central Intelligence Agency operating in Afghanistan are the only forces that deploy the pilotless aircraft in the region.

Officials in Washington say drone strikes are highly effective in the war against Al-Qaeda and its Islamist allies, killing a number of high-value targets, including Pakistan's Taliban founding father Baitullah Mehsud.

Separately, five Pakistani soldiers were killed in a Taliban attack on a check post in neighbouring South Waziristan region, security officials said Friday.

The militants launched their attack overnight on Talab check post in mountainous Sararogha district, they said.

"Five soldiers were killed and one is missing," a security official said, requesting anonymity.