Pakistani intelligence officials say a U.S. drone strike has killed at least six suspected militants in the country's northwest.

Two missiles hit a compound in the Shawal area of the North Waziristan tribal agency on Tuesday, in the latest strike to hit the al-Qaida and Taliban militant stronghold.

Officials told VOA's Deewa Radio that those targeted in the attack belonged to the al-Qaida-linked Haqqani network, believed to be based in North Waziristan. U.S. and Afghan officials blame the militant group for numerous attacks in neighboring Afghanistan.

Tuesday's drone strike comes despite Pakistani demands for the United States to end such attacks. Islamabad says they violate the country's sovereignty, while Washington considers drone attacks a key tool in its war against al-Qaida and the Taliban.

The Long War Journal, an online publication that reports on the global war against terrorism, says that in 2011 the U.S. carried out 64 drone strikes in Pakistan's northwestern tribal region.