Two US drone strikes on Thursday killed at least 10 militants in Pakistan's northwestern tribal belt including the brother of a Taliban commander, local officials said.

Four insurgents were killed in the first strike, when four missiles slammed into a pick-up truck in Azam Warsak, 20 kilometres (13 miles) west of Wana, the main town of South Waziristan tribal district, officials said.

In the second strike six militants were killed when four missiles hit a house in Hisokhel, 30 kilometres east of Miranshah, the main town of neighbouring North Waziristan tribal district, security officials told AFP.

The covert drone programme -- which US officials refuse to discuss publicly -- is the chief US weapon against Taliban and Al-Qaeda militants who use Pakistan's lawless tribal areas as launchpads for attacking US troops in Afghanistan.

The first strike indicates that US intelligence has penetrated the close family circle of Maulvi Nazir, a Pakistani commander who leads Islamist militants in battle against American troops across the border in Afghanistan.

"Nazir's younger brother Omar Wazir has been killed, it has been confirmed," a Pakistani security official told AFP. Another Pakistani intelligence official also confirmed his death.

Residents and security officials in the region described the 27-year-old as the operational head for the Nazir group, and a close aide to his brother.

He adopted a low profile, going to Afghanistan, assigning duties to fighters and supervising logistic arrangements for their missions, they said.

Another close relative of Nazir's was also among the dead, Pakistani security officials said, but the identities of the militants killed in the second strike were not immediately clear.

Thursday's strikes were the first for nearly two weeks, after four fighters were killed in the mountains further west of Wana on October 15.

Nearly 60 US drone strikes have been reported in Pakistan so far this year, dozens of them since Navy SEALs killed Al-Qaeda leader Osama bin Laden in the garrison city of Abbottabad, close to the capital Islamabad, on May 2.

Relations between Pakistan and the United States deteriorated sharply afterwards, and again over accusations that Pakistani intelligence was involved with the Haqqani network, blamed for last month's siege of the US embassy in Kabul.

Visiting Islamabad last week, US Secretary of State Hillary Clinton called on Pakistan to take action within "days and weeks" on dismantling militant havens and encouraging the Taliban into peace talks.

But although Pakistan recognised it could do more in clamping down on Afghan insurgents, it offered no details on how, and commanders are unwilling to launch a sweeping offensive in North Waziristan, base of the Haqqani Taliban faction.

On Thursday a US general accused Pakistani forces on the border of allowing insurgents to fire on American troops in Afghanistan.

"In some locations from time to time you will see what just appears to us to be a collaboration... or at a minimum a looking the other way," said Lieutenant General Curtis Scaparrotti, deputy commander of the NATO-led force in Afghanistan.

Clinton's visit to Islamabad was seen as papering over some of the divisions, including her admission that the US had held one exploratory meeting with the Haqqani network, facilitated by Pakistani government officials.

Pakistani policy makers have argued that military operations offer limited gains and that now is the time to concentrate on a comprehensive reconciliation ahead of the planned NATO withdrawal from Afghanistan.

Clinton told the House Foreign Affairs Committee on Thursday: "We look to Pakistan to encourage the Taliban and other insurgents to participate in an Afghan peace process in good faith -- both through unequivocal public statements and by closing off the safe havens."