KHAR, Pakistan: Pakistani security forces have launched a much-awaited “targeted operation” against militants in a restive northwestern district bordering Afghanistan, displacing thousands of residents who have fled to safer areas, officials said Tuesday.

There was no formal government announcement about the launch of the offensive in Bajaur, a former stronghold of the Pakistani Taliban in Khyber Pakhtunkhwa province, but a government administrator, Saeed Ullah, said that it was not a large-scale operation and only insurgent hideouts were being hit to avoid any civilian casualties.

Ullah estimated that about 20,000 families, or more than 50,000 people, have left their homes in recent days over fears about the operation.

Residents reported that security forces, backed by helicopters, struck militant hideouts in the mountainous areas along the Afghan border.

Pakistan carried out a major operation in Bajaur against Pakistani and foreign militants in 2009, displacing hundreds of thousands of people.