Islamabad - Jets from the North Atlantic Treaty Organization on Sunday bombed hills in Pakistan's Khyber tribal district, killing at least five people, Pakistani authorities quoting locals said.

The attack took place in Morga area in the remote Tirah valley, located close to the volatile Afghan border.

"The airstrike killed at least five people from the Qambar Khel tribe, while four or five more were wounded," an official in the area told Deutsche Presse-Agentur dpa on condition of anonymity.

Pakistan's north-western tribal region is considered a sanctuary for al-Qaeda and Taliban militants who fled Afghanistan after the US- led invasion following terrorist attacks in the United States in 2001.

International forces fighting the Taliban say fighters hiding in Pakistan's tribal districts routinely launch cross-border attacks on their troops, and ask Islamabad to "do more" to stop these infiltrations.

Pakistan has deployed around 120,000 troops along the treacherous frontier and stresses that the responsibility to stop the intrusions also lies with the security forces stationed in Afghanistan.

However, it clearly states that any action against the militants inside the Pakistani territory will be taken by its troops.

Relations between the Washington and Islamabad, two major allies in the United States' war against terrorism, have been strained by recent increase in the US airstrikes and a ground attack in the tribal belt.

Pakistani Prime Minister Yousaf Raza Gilani has warned US authorities that such operations could prove "counterproductive" and would fuel public anger against the United States. (dpa)