Pakistani intelligence officials say a suspected U.S. drone strike in northwestern Pakistan has killed at least 12 militants.

The officials said the unmanned aircraft fired several missiles Wednesday into a house in the South Waziristan tribal area near the Afghan border.

The strike comes a day after officials said a drone attack killed at least seven militants in Miranshah, the main town in neighboring North Waziristan.

U.S. officials have never publicly acknowledged drone strikes against militants in Pakistan's tribal areas but have anonymously confirmed such strikes to various news outlets.

Pakistan has condemned the strikes as a violation of its sovereignty, but they are believed to be carried out with the help of Pakistani intelligence.