The strike came as the US Joint Chiefs of Staff chairman, Adm. Mike Mullen, met with top military officials in Pakistan, a key US ally in the battle against extremists.

The six missiles struck a compound in the Nazai Narai area of South Waziristan. The hideout was known to be frequented by foreign fighters who were among the dead, two intelligence officials said.

The officials said agents were trying to get more details about the identities and nationalities of the dead. Army spokesmen were not immediately available for comment.

US missile strikes regularly pound extremist targets in the northwest. South Waziristan has witnessed several major Pakistani military operations since the Sept. 11 attacks on the United States. Washington has relied heavily on its covert missile campaign to take out Al-Qaeda, Afghan Taleban and their local supporters in North and South Waziristan tribal regions, which are hiding places for insurgents.

Most of the strikes have hit targets in North Waziristan - home to several militant networks that attack US forces in Afghanistan. Although Pakistan publicly condemns the missile strikes, it has secretly helped Washington in previous attacks.

Pakistan’s importance to the American war effort in Afghanistan has been underscored by how frequently top US political and military leaders swing through Islamabad and Rawalpindi, where the Pakistani army has its headquarters.

Adm. Mullen on Saturday met Gen. Tariq Majid, the ceremonial head of the Pakistan armed forces, and discussed regional security, an international conference held in Kabul this week and its effects on the region, Pakistan’s statement said.

The statement issued in Islambad added that “India-Pakistan confidence-building, progress on efforts by Pakistan against terrorism and violent extremism and other matters of bilateral interest” were also discussed.   Mullen will later meet US officers overseeing military assistance to Pakistan, as well as Pakistan’s powerful army chief, Gen. Ashfaq Kayani, whose term was extended by three years on Thursday.

“This visit to Pakistan is part of the regular bilateral consultations between the US and Pakistan,” the US embassy said in a statement.

Mullen and US officials have praised Pakistan for moving against militants in the northwest but have urged the military to expand its operations to include the Haqqani network, which is based in North Waziristan.

On the eve of his one-day visit, Mullen acknowledged US worries over sanctuaries in Pakistan for extremists, including the Haqqani network, who have attacked international forces in neighboring Afghanistan. Speaking at news conference in New Delhi, Mullen called the Haqqani militants “the most lethal network” faced by the US-led international force in Afghanistan and said he had repeatedly urged Pakistan to tackle the threat.

“I continue to address that with the (Pakistani) leadership as a very, very strong priority,” Mullen told reporters at the end of a two-day visit to India.

Mullen was due to take an aerial tour at an unspecified location in the north, where Kayani planned to brief him on Pakistani operations against Taleban militants, US officers said.

Prime Minister Yousaf Raza Gilani announced on Thursday he had extended Kayani’s term for three years, a move welcomed by US officials who credit the general for launching offensives against Taleban militants last year.

— With input from agencies