Militants escaped a US drone strike targeting a vehicle in a troubled Pakistani tribal region near the Afghan border on Tuesday, security officials said.

The missile strike took place in the South Waziristan tribal district, where the Pakistani military launched an operation against Islamist militants in 2009.

"A US drone fired two missiles targeting a vehicle parked in a compound but the militants fled before they could be hit," a security official told AFP.

He said the number of militants present in the vehicle before the strike was not immediately known.

Two other security officials confirmed the strike in Azam Warsak town, which is 15 kilometres (nine miles) west of Wana, South Waziristan's main town. They also said there were no casualties.

The latest missile attack came with tensions running high between Pakistan and the United States over Washington's demand for action against the Taliban-allied Haqqani militant network.

The leaders of the Al-Qaeda-linked Haqqani group are based in North Waziristan.

The US has accused the network of orchestrating the recent attacks on its embassy in Kabul and a NATO base in Afghanistan, with Pakistani intelligence involvement.

The United States does not confirm drone attacks, but its military and its Central Intelligence Agency (CIA) operating in Afghanistan are the only forces that deploy them in the region.

The covert US strikes cause anti-American hostility among the Pakistani public, who see foreign military action on Pakistani soil as a violation of national sovereignty.

Around two dozen drone strikes have been reported in Pakistan since elite US forces killed Al-Qaeda chief Osama bin Laden in a suburban home near Pakistan's main military academy in Abbottabad, close to the capital, on May 2.

Pakistani-US relations sank to a new low after the unilateral American raid that killed bin Laden, but in recent months appeared to recover slightly.

Pakistan has so far not acted on calls from Washington to launch a decisive military campaign in North Waziristan, as it has done elsewhere in the tribal belt.

And senior security official told AFP on Monday that Pakistan would not launch an offensive in North Waziristan despite Washington ramping up the pressure.

He said the military needs to "consolidate gains" made against local militants who pose a security threat elsewhere in the tribal region, which Washington has branded an Al-Qaeda headquarters.

Pakistan has around 140,000 troops based along the northwest, which borders Afghanistan, and says more than 3,000 of its soldiers have been killed since 2001 -- more than the number of Western soldiers who have died in Afghanistan, which stands at over 2,700.