MIRANSHAH: A US drone attack destroyed a vehicle in Pakistan's tribal district of North Waziristan on Friday, killing at least three suspected militants, Pakistani security officials said.

Two missiles slammed into the vehicle in the semi-autonomous northwestern district considered the heartland of militants in Pakistan and the focus of a dramatic increase in US drone strikes since early September.

Pakistani officials reported the attack as US President Barack Obama and Nato leaders flew to Lisbon for a summit designed to set a date to hand control of the fight against the Taliban in Afghanistan to local forces in 2014.

“Two missiles were fired on a vehicle. So far three militants are confirmed killed in this attack,” a senior Pakistani security official told AFP on condition of anonymity.

Local intelligence officials said the dead belonged to the Taliban and Al-Qaeda linked Haqqani network, but it was not immediately clear whether they included any high-value targets.

They said up to four militants were killed when the vehicle exploded into a fireball in Naurak village, about 15 kilometres (nine miles) east of Miranshah, the main town in North Waziristan.

The Haqqani network has been accused of plotting some of the deadliest attacks on US troops in neighbouring Afghanistan, including a suicide bombing that killed seven CIA operatives at a US base in Khost last December.

More than 220 people have been killed in over 40 strikes since September 3, as intelligence claims emerged last month of a plot to launch commando attacks on European cities.

The United States considers Pakistan's tribal belt an Al-Qaeda headquarters and the most dangerous place on Earth, and has reportedly criticised Pakistan's failure so far to launch a major ground offensive in North Waziristan.

Friday's drone strike comes three days after a similar attack killed at least 15 militants and destroyed a training centre north of Miranshah.