Islamabad: Pakistan stands with the US against international terrorism, the Muslim nation's presidential front-runner wrote in a column that appeared on Thursday amid growing furor over an American-led cross-border attack in Pakistani territory.

The raid in the South Waziristan tribal region was the first known foreign ground assault in Pakistan against a Taliban haven. The Pakistani government summoned the US ambassador to protest the incursion, which officials said killed at least 15 people, including civilians.

An American official, speaking on condition of anonymity because of the sensitivity of cross-border operations, confirmed that US troops conducted the raid Wednesday about 1.6 kilometres beyond the Afghan frontier.

The boldness of the thrust fed speculation about the intended target. But it was unclear whether any extremist leader was killed or captured in the operation in one of the militant strongholds dotting a frontier region considered a likely hiding place for Osama Bin Laden and Al Qaida's No. 2 leader, Ayman Al Zawahri.