New Delhi, March 18 -- Rescuers recovered more bodies from the rubble of a drug rehabilitation hospital in Kabul on Tuesday after officials said an overnight airstrike killed more than 400 people in a dramatic escalation of a conflict between Pakistan and Afghanistan that is now in its third week.

Pakistan rejected Afghanistan's accusation that it targeted the Omid Addiction Treatment Hospital, insisting its strikes across eastern Afghanistan on Monday were against military facilities. It also dismissed Afghan claims of hundreds of casualties as propaganda.

The casualties were taken to several hospitals in the area, where crowds gathered to search for their loved ones among the injured and the dead. It was not possible to independently ...