Islamabad, Jun 2: A US drone targeted a vehicle in the south Waziristan tribal region of Pakistan today, killing four militants in the latest in a string of attacks by the CIA-operated spy planes.
The drone struck in Khwashi Khel village, a short distance from Wana, the main town in South Waziristan Agency, TV news channels quoted officials as saying.
There have been six drone strikes since May 23.
Most of the strikes have been carried out in North Waziristan Agency, described by US and Afghan officials as a safe haven for Taliban and Al Qaeda elements.
The US stepped up drone strikes shortly after the conclusion of the NATO Summit in Chicago, where Pakistan did not make any announcement about ending a six-month blockade of supply routes to Afghanistan.
The supply lines were shut after a cross-border NATO air strike killed 24 Pakistani soldiers in November last year.
The drone strikes have added to tensions between the US and Pakistan, which has described the attacks as a violation of its sovereignty and called for them to be stopped.
The US had eased its drone campaign in Pakistan's tribal areas after a CIA contractor was arrested for shooting and killing two Pakistani men in Lahore early last year and the unilateral American raid that killed Osama bin Laden in Abbottabad in May last year.