A major salvo of US missiles on Wednesday destroyed a Pakistani Taliban base on the Afghan border, killing up to 18 militants including possible Al-Qaeda fighters, local officials said.
Five US drones fired up to 10 missiles into a sprawling compound in the Baber Ghar area of South Waziristan, killing 15 to 18 fighters in the deadliest American strike reported by Pakistani officials in three months.
US officials say Pakistan's tribal belt provides sanctuary to Taliban fighting for 10 years against US troops in Afghanistan, Al-Qaeda groups plotting attacks on the West and Pakistani Taliban who routinely bomb Pakistan.
Five US drones carried out Wednesday's attack, one of the officials told AFP in the heaviest coordinated strike in northwest Pakistan since a similar strike killed 21 fighters in the Afghan Taliban Haqqani faction on August 10.
"The target was a base of Pakistan Taliban. We have reports that 16 to 18 militants were killed," the official told AFP in the northwestern city of Peshawar. Another official in Peshawar put the death toll at 15.
An official in Wana, the main town of South Waziristan, confirmed that a base of Pakistan's umbrella Taliban faction, Tehreek-e-Taliban, was destroyed and said there were reports that "some foreigners" were also killed.
Pakistani officials typically use the word "foreigner" to denote Al-Qaeda and Uzbek Islamist militants.
"It was Taliban base. They were using this place as a training camp, to keep weapons and to take shelter," the Wana official said. "The drones came almost at the same time," he added.
Officials said the attacks came minutes apart at around 2:30 am (2130 GMT Tuesday) about three kilometres (two miles) from the border of Afghanistan's Paktia province, one of the flashpoints in the 10-year Taliban insurgency.
Wednesday's strike was the 63rd so far this year, according to an AFP tally.
Elsewhere in the tribal belt on Wednesday, five men and a 12-year-old boy were killed when a remote-controlled bomb exploded near a passenger van in the troubled Tirah valley of Khyber district, local official Mutahir Zeb said.
He said that most of the passangers in the van belonged to the Kukikhel tribe, which is opposed to local militant group Lashkar-e-Islam.
Nine people, including two women, were also wounded, Zeb added.
The Pakistani army has launched a series of offensives targeting Laskhar-e-Islam, a Taliban-allied militant group waging a local insurgency.
Separate Taliban attacks on military convoys Wednesday killed an officer and a soldier in the troubled district of Kurram and in Ladha town in South Waziristan respectively, security officials told AFP.
Both officials requested anonymity as they were not authorised to talk to the media.
"Several militants were also killed in retaliatory fire," one official said of the Kurram attack.
The US refuses to publicly discuss drone strikes in Pakistan, but the programme has dramatically increased as the Obama administration searches for an end to a decade of fighting in Afghanistan.
The Pakistani government has quietly assented to the programme despite popular opposition at home, where anti-Americanism is frequently exploited by nationalist politicians and the conservative religious right.
The drone strikes have also been credited with killing some of Islamabad's biggest enemies -- such as Baitullah Mehsud, the founder of Pakistan's Taliban movement blamed for the majority of bomb attacks that have killed thousands.
Pakistan-US ties deteriorated sharply this year over a unilateral American raid that killed Osama bin Laden in May and over accusations that Pakistani intelligence was involved in a September siege of the US embassy in Kabul.
At talks in Islamabad last month, US Secretary of State Hillary Clinton called on Pakistan to take action within "days and weeks" on dismantling Afghan militant havens and encouraging the Taliban into peace talks.
But with Islamabad a key ally in the war in Afghanistan -- the bulk of NATO supplies still route through Pakistan to landlocked Afghanistan -- US action against militants on Pakistani soil is limited to the covert drone strikes.
There is also a growing debate in Washington about further limiting aid to Pakistan, perceived to play a double game with the Taliban, unless the government does more itself to neutralise the threat.