A third US drone attack in 24 hours targeted Islamist fighters in Pakistan's tribal belt on Thursday, killing five militants, including three Arabs, security officials said.

Two missiles struck a compound in Ismail Khel village in North Waziristan, considered the premier fortress of Taliban and Al-Qaeda-linked militants on the Afghan border and the focus of a dramatic increase in US strikes.

The village lies about 40 kilometres (25 miles) west of Miranshah, the main town in the semi-autonomous tribal district.

"The target was a militant compound," one official said. "Three Arabs, one Afghan and one local were killed in the attack."

Another official said at least two others were injured in the attack.

It was not immediately clear if the casualties included any high-value targets, officials said.

The United States considers Pakistan's tribal belt an Al-Qaeda headquarters and many Western officials say the drone campaign is seen as integral to US-led efforts to turn around a nine-year Taliban insurgency in Afghanistan.

Afghan and US officials allege that militants use rear bases in Pakistan to orchestrate attacks and that rebel networks enjoy at least some measure of protection from the Pakistani intelligence services -- charges that Islamabad denies.

Thursday's US drone strike was the third in around 24 hours in North Waziristan, killing a total of 11 suspected militants since Wednesday.

The missiles slammed into the building as the body of a militant killed in a drone strike on Wednesday was being brought to the compound -- owned by Alif Deen, a relative who perished in Thursday's attack, a security official said.

Pakistani officials said two drone strikes on Wednesday targeted a car carrying members of the Haqqani network and a house harbouring foreign fighters, killing up to six in North Waziristan.

The Taliban and Al-Qaeda-linked Haqqani faction is one of the toughest opponents of US troops in Afghanistan and was suspected of playing a role in a December 30 suicide attack on a CIA base that killed seven intelligence agents.

The covert US drone campaign stepped up strikes in Pakistan's tribal belt on the Afghan border last month over intelligence claims of a Mumbai-style terror plot to launch attacks on European cities.

Around 35 such attacks since September 3 have killed more than 185 people, according to an AFP toll. Around 150 drone strikes since August 2008 have killed more than 1,200.

Despite US pressure on Pakistan to launch its own ground and air offensive in North Waziristan, the military has deferred any major operation until it has beaten back homegrown Taliban from other parts of the mountainous tribal belt.

The White House said this week that US President Barack Obama and his Pakistani counterpart Asif Ali Zardari agreed by telephone that more needs to be done to combat terror groups in Pakistan.

The war in Afghanistan is now at its deadliest, killing at least 603 foreign soldiers so far this year and thousands of civilians since the 2001 US-led invasion brought down the Taliban regime.

But in Pakistan, drone attacks are seen as a violation of sovereignty and have been used as a justification by Islamist militants who attack NATO supply convoys destined for Afghanistan and bomb Pakistani security targets.

Secretary of State Hillary Clinton has said the US administration would ask Congress to approve two billion dollars in military aid from 2012 to 2016, satisfying a key request of Pakistan's influential military.