Pakistan on Saturday lodged protest with the United States over its air strike in Pakistan's tribal region which caused the loss of innocent civilians, Pakistani foreign office said.

"The foreign office has lodged a protest with the U.S. Ambassador in Islamabad," the foreign office said in a statement.

"Pakistan will also take up this matter in the next meeting of Tripartite Commission," it said.

The Tripartite Commission groups Afghanistan, Pakistan and the United States and the forum mainly reviews border security and cooperation among the security forces of the three countries.

"According to preliminary investigations there was foreign presence in the area and that in all probability was targeted from across the border in Afghanistan," the statement said.

The statement also condemned the loss of innocent civilian lives in the incident.

The incident in Pakistan's Bajaur tribal area is being thoroughly investigated and that the investigations are still continuing.

However, the statement did not mention U.S. media reports that Ayman al-Zawahiri, Osama bin Laden's deputy, might have been killed in the air strike.

American TV channels have reported that a CIA airstrike on Bajaur might have killed Ayman al-Zawahiri.

Earlier, Information Minister Sheikh Rashid also denied the killing of Ayman al-Zawahiri but admitted the presence of some foreigners in the tribal region and asked the tribesmen to rid all tribal areas of foreign intruders. He said that foreign militants had been responsible for all the misery and violence in the region.

"Pakistan wants to assure the people that the government will not allow such incident to reoccur," he added.

Source: Xinhua