Two separate US missile strikes targeting Al-Qaeda-linked fighters in Pakistan's northwest tribal belt on Wednesday killed 17 militants, local security officials said.

A pre-dawn attack was directed at the Haqqani network, officials said, a Pakistan-based group with links to both Al-Qaeda and the Taliban and one of the toughest foes for foreign forces in the war in neighbouring Afghanistan.

This month alone, a surge in US missile strikes has now killed 85 militants in the lawless tribal belt on the Afghan border, an area Washington has branded a global headquarters of Al-Qaeda and the most dangerous spot on Earth.

With Pakistan struggling to cope with devastating floods that have hit 21 million people in the country's worst humanitarian disaster, Islamist militant violence has picked up in recent weeks with a wave of major bombings.

The Taliban last week threatened Pakistani security forces with more suicide attacks to avenge the US missile strikes, which have become a key tactic in the US-led war to reverse the insurgency in Afghanistan.

"Several US drones fired eight missiles at two militant compounds early this morning, killing at least 12 militants," a senior security official told AFP of the first attack.

"The missile strike targeted militants of the Haqqani network."

The barrage hit the village of Dargah Mandi on the outskirts of Miranshah, the main town in North Waziristan tribal district, where US missiles also killed 15 militants in two separate attacks Tuesday.

Created by Afghan warlord Jalaluddin Haqqani and run by his son Sirajuddin, the Haqqani network is linked to both Al-Qaeda and the Taliban and has become a particularly prickly thorn in the side of US-led forces trying to bring security to eastern Afghanistan.

Residents said the targeted houses had been rented out to militants by a local tribesman and were destroyed in the attacks, which caused panic in the village.

"As the US drones came over the village people started shouting and running here and there shouting 'run, drones have come,'" one local tribesman told AFP, requesting anonymity for fear militants might harm him.

The intelligence official put the number of missiles fired at 10, saying several drones came from all directions, while another said three militants were also wounded in the strike.

The second attack later Wednesday targeted a militant compound in Payekhel village of Datta Khel district of North Waziristan, killing five rebels and wounding three others, local security officials said.

On Tuesday, 11 militants were killed in an attack by the unmanned bombers on the village of Bushnarai in Shawal district, a known stronghold of Taliban warlord Hafiz Gul Bahadur that is populated by Arab fighters.

Another four were killed in Qutabkhel village south of Miranshah when US drones fired missiles on militant vehicles, officials said.

US forces have been waging a drone war against Taliban and Al-Qaeda-linked commanders in the northwest, where militants have carved out havens in mountains outside direct government control.

Officials in Washington say the drone strikes are a vital tool needed to protect foreign troops in Afghanistan and have killed a number of high-value targets including Pakistani Taliban chief Baitullah Mehsud.

Although the US military does not as a rule confirm the attacks, its armed forces and the Central Intelligence Agency operating in Afghanistan are the only forces that deploy pilotless drones in the region.

Under US pressure to crack down on Islamist havens on the border, Pakistan has in the past year also stepped up military operations against largely homegrown militants in the area.

An Islamist militant bombing campaign has killed more than 3,700 people and fanned instability across nuclear-armed Pakistan since July 2007, with a spike in attacks this month against security forces and Shiite worshippers.

Over 1,100 people have been killed in 130 drone strikes in Pakistan since August 2008, including a number of senior militants. However, the attacks often serve to fuel anti-American sentiment in the conservative Muslim country.