Kabul's police chief, Gen. Zahir Zahir, has resigned after Taliban gunmen killed three members of a South African family in the capital, while officials said Afghan forces had ousted insurgents trying to seize former U.S. and British base Camp Bastion in the south.

Taliban fighters breached the perimeter of Camp Bastion in the southern Afghan province of Helmand last week, just one month after the base was handed over to the Afghan army.

The latest Taliban attacks have dented confidence in the country's security force and added to concern the police and army will struggle to hold strategic territory after most foreign troops pull out at the end of 2014.