Islamabad - Admiral Mike Mullen, chairman of the US Joint Chiefs of Staff, and Pakistani commanders on Wednesday discussed the security situation along the Afghan frontier, where US pursuit of al-Qaeda and Taliban militants has strained relations between the two allies, officials said.

Mullen met Pakistan's military chief, General Ashfaq Parvez Kayani, in the garrison town of Rawalipindi weeks after both officers reviewed the counter-terrorism strategy aboard the aircraft carrier USS Abraham Lincoln in the Indian Ocean.

The talks focused on cooperation between the US and Pakistani forces against international terrorism and recent incursions by American troops into Pakistan.

"General Kayani expressed his serious concerns on US attacks inside Pakistan and emphasized that the foreign troops could not be allowed to conduct operations on Pakistani soil," an official privy to the discussions said on condition of anonymity.

Both top officers later met with Pakistani Prime Minister Yousaf Raza Gilani in Islamabad.

Mullen is undertaking the previously unannounced visit as relations between the two countries have been strained by increasing US military operations inside Pakistan, including the first known ground raid that killed 20 people, mostly women and children, on September 3.

A week after the assault that came amid missile strikes by US drones, Kayani in a strongly worded statement said that country's sovereignty would be defended "at all cost." He added that "such reckless actions only help the militants and further fuel militancy in the area."

Pakistan's north-western tribal regions are considered safe havens for al-Qaeda and Taliban leaders who have regrouped and established facilities to train fighters for attacking coalition forces in Afghanistan.

Mullen recently said the US was not winning its war in Afghanistan and, therefore, needed a "new, more comprehensive strategy," sparking speculation that the US was increasing its focus on independent operations inside Pakistani territory to eliminate key targets.

A following New York Times report that US President George W Bush had secretly approved ground attacks without the consent of Pakistan gave credence to the reports of changing US tactics.

However, the Pakistani military insists that it reserves the right to defend the territorial integrity of the country. Security officials on Monday said government troops and tribesmen prevented a US incursion into South Waziristan tribal district's Angor Adda village, the scene of an earlier ground assault. (dpa)