Pakistan held funerals Sunday for the 24 soldiers killed Saturday in a NATO cross-border airstrike in the northwest region of the country.

NATO chief Anders Fogh Rasmussen said Sunday he has offered his condolences to Pakistan's Prime Minister Yousuf Raza Gilani for the “tragic, unintended” deaths.

Rasmussen said that he has written to the prime minister to say that the deaths of the Pakistani troops are “as unacceptable and deplorable as the deaths of Afghan and international personnel.” He said he supports the NATO investigation currently under way.

Earlier Sunday, Pakistan's Foreign Minister Hina Rabbani Khar told U.S. Secretary of State Hillary Clinton the air raid on the military outposts that killed the soldiers and wounded 14 others is not acceptable. Khar said the attack demonstrated a complete disregard for human life.

Pakistan retaliated to the airstrike by shutting down all NATO supply lines through its territory to Afghanistan and ordering the U.S. to vacate an air base in southwestern Baluchistan province within 15 days.

Prime Minister Gilani and top military and government leaders said Saturday the Pakistani government “will revisit and undertake a complete review of all programs, activities and cooperative arrangements with US/NATO/ISAF.” They called for “strong and urgent action” against those responsible for the deadly incident.