Taliban fighters overran three provincial capitals including the strategic northeastern city of Kunduz on Sunday, local officials said, as the insurgents intensified pressure on the north and threatened further cities.

The insurgents have taken dozens of districts and border crossings in recent months and put pressure on several provincial capitals, including Herat in the west and Kandahar in the south, as foreign troops withdraw.

The offensive has gathered momentum in recent days after the United States announced it would end its military mission in the country by the end of August.

Taliban fighters seized...