Islamabad, Pakistan (CNN) -- A U.S. drone strike targeting a militant compound in Pakistan's volatile tribal areas along the border with Afghanistan has killed 16 people, Pakistani security officials said Wednesday.
The officials said the attack early Wednesday struck a compound of the Haqqani Network, a group that carries out attacks against NATO forces in Afghanistan and travels back and forth across the porous border between Afghanistan and Pakistan.
The strike killed 16 militants and wounded five others in the Dande Darpakhel area near Miranshah in North Waziristan, the officials said, speaking on the condition of anonymity. Officials had earlier given a higher death toll of 17.
It wasn't immediately clear if any high-profile insurgent figures had been killed in the attack. The militants in the compound were from both Pakistan and Afghanistan, the officials said.
The U.S. government has said strikes by the unmanned aircraft are a necessary part of the fight against militant groups. But the attacks have drawn deep opposition in Pakistan because of civilian casualties and the violation of sovereignty.
The Pakistani government "strongly condemns the U.S. drone strike that took place in Miranshah," the country's foreign ministry said in a statement.
"The Government of Pakistan has consistently maintained that drone strikes are counter-productive, entail loss of innocent civilian lives and have human rights and humanitarian implications," the ministry said.
Pakistani Prime Minister Nawaz Sharif has called for the United States to halt drone strikes in the country. Wednesday's attack appeared to be the deadliest since Sharif took office last month.
In May, U.S. President Barack Obama defended the use of the drone program, but he stopped short of directly commenting on the strikes in Pakistan.
Relations between Washington and Islamabad have been strained since the U.S. raid inside Pakistan in May 2011 that killed al Qaeda leader Osama bin Laden. The United States carried out the raid without notifying Pakistani authorities.
Ties soured further after a NATO airstrike killed 24 Pakistani soldiers at a checkpoint near the Afghan border in November 2011. The drone strikes cause continued friction.
In another outbreak of violence in the Pakistani tribal areas early Wednesday, officials said more than 50 militants attacked a checkpoint of the Frontier Constabulary, a paramilitary force.
The attack to place about 40 kilometers southeast of the main city in the region, Peshawar, at a post where 15 members of the constabulary were stationed, said the force's chief, Commandant Majeed Marwat.
Six constabulary members were killed during the hour-long firefight that ensued, and seven others were wounded, Marwat said.
The constabulary was unable to provide any information on militant casualties from the clash.
CNN's Saima Mohsin reported from Islamabad, and Jethro Mullen reported and wrote from Hong Kong. Journalist Zahir Shah Sherazi contributed to this report.