The Taliban on Wednesday launched their first assault on a provincial capital in Afghanistan, since waging a major offensive against government forces, local officials said.

Fierce fighting has erupted in the western city of Qala-i-Naw, the capital of Badghis, after the militants captured all the surrounding districts of the province.

"The enemy has entered the city, all the districts have fallen. The fighting has started inside the city," Badghis governor Hessamuddin Shams told reporters in a text message.

Badghis provincial council chief Abdul Aziz Bek and council member Zia Gul Habibi confirmed that fighting between the Taliban and government forces had erupted inside the city.

"Fighting continues in different parts of the city right now," Bek told AFP, adding that some security officials had surrendered to the Taliban during the night.

Provincial council member Habibi said the Taliban were inside the police headquarters of the city and the local office of the country's spy agency, the National Directorate of Security.

"The provincial council officials have fled to an army camp in the city. Fighting continues in the city," she said.