PESHAWAR, Pakistan (Reuters) - Pakistan condemned an attack on militants by U.S. drone aircraft on Wednesday, the first such strike in the controversial program in nearly a month.
The missiles, fired from two unmanned planes, hit a vehicle carrying militants in a village about 12 km (eight miles) east of the Afghan border in South Waziristan, residents and officials said.
"We have confirmation of six (dead) but the toll could be high," a security official said.
The United States has used drone attacks to target al Qaeda-linked militants over the past few years in Pakistan's tribal areas but they have become a source of concern for the Pakistan government because of civilian casualties.
Pakistan's Foreign Office strongly condemned the latest attack and said it had protested to the U.S. ambassador.
"We have repeatedly said that such attacks are counterproductive and only contribute to strengthen the hands of the terrorists," it said in a statement.
"Drone attacks have become a core irritant in the counter-terror campaign. Pakistan has taken up the matter with the U.S. at all levels."
Prime Minister Yusuf Raza Gilani, speaking in the National Assembly, also said the attacks turned people against the government.
"We admit we are against them. We were able to separate militants from local tribal people, and when drone attack takes place the local tribes get united with militants," Gilani said.
Wednesday's strike was made two days after Lieutenant-General Ahmad Shuja Pasha, head of Pakistan's Inter-Services Intelligence, sought an end to the drone campaign in a meeting in Washington with CIA Director Leon Panetta, officials said.
It was the first since March 17, when a similar attack killed 38 tribal elders and suspected militants and drew rare condemnation from the country's powerful military chief.
An intelligence official said the United States acted without any Pakistani help.
In March, Pakistan refused to attend a meeting to discuss the conflict in Afghanistan in protest against the strike in North Waziristan tribal agency, a known hub for al Qaeda and Taliban militants on the Afghan border.
Ties between the intelligence agencies of the United States and Pakistan soured further over the case of Raymond Davis, a CIA contractor who shot dead two Pakistanis in the eastern city of Lahore in January.
Pakistan held Davis despite U.S. insistence that he had diplomatic immunity. He was released last month after the families of the dead men were paid compensation, a custom in Pakistan and sanctioned in Islam.
(Reporting by Chris Allbritton, Hafiz Wazir and Saud Mehsud; Editing by Angus MacSwan)