ISLAMABAD, Pakistan -- The head of the World Health Organization's polio eradication program in Pakistan says one of its doctors and a driver were wounded when their vehicle came under fire in the port city of Karachi.

Dr. Elias Durry says the doctor is an international volunteer helping supervise the polio eradication program. He says the doctor was wounded Tuesday in the abdomen and is undergoing surgery.

Pakistan is in the second day of a three-day campaign to vaccinate children under five. Taliban militants in northern Pakistan have banned the vaccination, saying it can't go forward until the U.S. stops drone strikes in Pakistan.

Durry says it was not known whether the doctor was targeted or was accidentally caught in the crossfire.

He says WHO remains committed to polio eradication in Pakistan.