At least five people are reported to have been killed in a missile attack in Pakistan's North Waziristan region.
Local people say the missile was launched from an unmanned drone aircraft and that the dead were believed to be militants.
The Pakistan military says it was not involved in the incident in the village of Danday Darpakhel.
In Washington the Pentagon has denied that a US drone plane from Afghanistan was involved.
"Every indication was that there was no US military involvement in this activity that you've seen," Pentagon spokesman Bryan Whitman said, the Associated Press news agency reports.
Correspondents say that US forces based in Afghanistan have used drones in the past to attack militants in Pakistan.
"A drone was flying very low and fired the missile. It destroyed three houses," a villager told the Reuters news agency.
"I have seen human flesh scattered all over the area near the houses."
North and South Waziristan have been at the centre of fighting between the army and Taleban and al-Qaeda militants.
The Pakistan military has frequently denied giving permission for US forces to carry out strikes on its soil.