Afghan security forces take their positions during a gun battle in Kunduz city on Tuesday.

Reuters/Kabul

Afghan forces backed by US air support battled Taliban fighters for control of the northern city of Kunduz on Tuesday, after the militants seized a provincial capital for the first time since their ouster 14 years ago.

The sudden fall of Kunduz on Monday was a major setback for the government of President Ashraf Ghani, which marked its first year in power on Tuesday, and raised questions over how ready Afghan forces were to tackle the Islamist insurgency alone.

Ghani announced in a televised address that more reinforcements were on their way to regain the city, which he said had fallen partly because government forces had shown restraint to avoid civilian casualties.

"The government is responsible, and cannot and will not bomb its own citizens."

Supply lines to Kunduz city had been interrupted by fighting in surrounding areas, according to Western and Afghan security officials.

To the south, clashes in Baghlan province closed a main route from the capital Kabul, while one convoy carrying security personnel was ambushed by Taliban insurgents.

Further afield, and independent of the action around Kunduz, fighting broke out in Nangarhar province bordering Pakistan.

At least 30 insurgents claiming loyalty to Islamic State were killed when militants attacked police checkpoints in Achin district, said Nangarhar police spokesman Hazrat Hussain Mashriqiwal. An official said four security personnel also died.

Several small groups have broken away from the Taliban to follow Islamic State, which security experts fear will seek to exploit any divisions in the dominant Afghan militant movement.

Taliban spokesman Zabihullah Mujahid said one reason for the assault on Kunduz was to prove that the group was still united, after the appointment of a new leader in July had angered many key figures.

Casualties unknown

Earlier in the day, the government said its forces had regained the Kunduz city prison and provincial police headquarters, which were overrun on Monday night, but the Taliban quickly refuted the claim.

More than 100 Taliban fighters were among the 600 prisoners who escaped during the jail attack, National Directorate of Security chief Rahmatullah Nabil told reporters on Tuesday.

US military planes struck Taliban positions on the outskirts of the city, a Nato spokesman said. The attack at about 9 am marked the first US air strike to defend Kunduz.

Colonel Brian Tribus, a spokesman for the Nato-led coalition, denied reports later in the day that there had been civilian casualties in the air strike.

Police said 83 Taliban were killed in the US action, a claim also denied by the Taliban.

Afghan Defence Minister Mohammad Masoom Stanekzai told reporters that 17 Afghan security personnel had been killed and 18 wounded in the past 24 hours across the country.

Taliban spokesman Zabihullah Mujahid said three militants had died and 11 were wounded, while at least 18 Afghan police had been killed.

At a trauma centre run by Medecins Sans Frontieres in Kunduz, six doctors remained on duty, scrambling to treat 150 patients on Monday night who crammed into offices and corridors.

The hospital was struggling to get medical supplies due to road closures, said Heman Nagarathnam, head of programmes in the Kunduz MSF facility.

‘Winning hearts’

Residents in Kunduz said the Taliban were patrolling the streets in vehicles they had seized from the army, police and Western aid agencies.

"Since yesterday they gained control of our hospital, central bank and other government buildings," said Abdul Ahad, a doctor at the 200-bed hospital in the city.

"They have been behaving very well with everyone, especially doctors. They may win people's hearts if they stay longer."

A senior commander in the hardline Islamist movement, which imposed strict Islamic law over Afghanistan for five years before it was toppled by US-led military intervention in 2001, said fighters had been ordered to treat locals well.

"Mullah (Akhtar) Mansour directed his commanders in northern Afghanistan to take care of the local community by winning their hearts and minds through good behaviour and self-respect instead of bullets," he said, referring to the Taliban's new leader.

The commander added that the insurgency would not stop at Kunduz.