ISLAMABAD: Humanitarian agencies active in Pakistan's northwest have been quietly told to prepare for up to 365,000 displaced people in advance of a military offensive against North Waziristan, a senior official with an international humanitarian agency said on Monday.

The official, who requested anonymity because of the sensitivity of the subject, was responding to a media report in a local newspaper that Pakistan will launch a military offensive against al Qaeda and Taliban safe havens in the Afghan border regions.

“Humanitarian agencies operating in FATA and Khyber-Pakhtunkhwa were given the heads up two weeks ago by the authorities of a possible displacement of up to 50,000 families,” he said, referring to the Federally Administered Tribal Areas and the northwest province.

A similar tip-off in 2009 preceded a military offensive in neighbouring South Waziristan by about five months, he said.

Other aid agencies were not immediately available for comment. The report comes just days after US Secretary of State Hillary Clinton reiterated a US demand to tackle sanctuaries for al Qaeda and the Taliban on the Afghan border.

An understanding for an offensive in North Waziristan, the main sanctuary in Pakistan for militants fighting in Afghanistan, was reached when Clinton and Chairman of the Joint Chiefs of Staff Admiral Mike Mullen visited Pakistan last week, the News reported.

The United States has long demanded that Pakistan attack the region to eliminate the Haqqani network, one of the deadliest Afghan militant factions fighting US troops in Afghanistan.

Pakistan has been reluctant to do so, but it has come under more pressure and its performance in fighting militancy is under scrutiny again after it was discovered that Osama bin Laden had been living in the country.

Some analysts say any joint US-Pakistani operation would subject the army to even more public criticism in a country where anti-US feeling runs deep.

“The reaction could be even more vociferous, just because everybody is so suspicious, as well as dismissive of American interference,” said Imtiaz Gul, author of “The Most Dangerous Place”, a book about Pakistan's militant strongholds.

“People already feel so humiliated because of this Osama bin Laden thing and now they will have another reason to react.”

But the South Asian nation, dependent on billions of dollars in US aid, is under more pressure than ever to show it is serious about tackling militancy.

Attacking US enemies in North Waziristan may be one way of repairing ties with Washington which were badly damaged by the bin Laden affair.

Pakistan maintains about 140,000 troops in the northwest, including about 34,000 in North Waziristan, but says they are too stretched fighting Pakistani Taliban insurgents in other parts of the region to tackle North Waziristan.