Taliban fighters have launched an attack on Ghazni, clashing with Afghan forces and using explosives in an attempt to seize the central Afghan city, local officials said on Tuesday.

The assault on Ghazni, on the highway linking the capital Kabul with the southern province of Kandahar, ramps up the Taliban's offensive against the government and comes as foreign troops prepare to exit from the war-torn country in less than three months.

While senior Afghan officials confirmed the Taliban's offensive, they also said that Afghan forces were trying to regain control of lost ground.

The Taliban have had a strong presence in the province of Ghazni for years, but provincial police officials said the overnight attack from several directions was the fiercest launched by the insurgents.

Clashes intensified near security checkpoints in the Shaikh Ajal and Ganj area of Ghazni city, forcing shopkeepers to shut the main market.

"The situation in Ghazni is changing, most of the lost areas in the outskirts are being taken back by the Afghan forces," said Abdul Jami, a provincial council member in Ghazni.

Roads into the area were closed and telecoms interrupted making it hard for aid groups and officials to assess the number of casualties.

As Afghan forces battle the Taliban in Ghazni and other parts of the country, officials said young civilians were actively joining the battle against the hardline Islamist group.

Ajmal Omar Shinwari, a spokesman for the Afghan defence and security forces, said Afghans keen to take up arms against the Taliban are being absorbed in the structure of territorial army forces.

"First they will be trained then they will be deployed to the battlefield along with other Afghan security forces," said Shinwari in capital city Kabul.

Violence surged after the US and NATO military began the withdrawal of their last remaining troops to meet a Sept. 11 deadline announced by President Joe Biden to end America's longest war.

Amid the rising violence, President Ashraf Ghani visited Washington last week to meet Biden, who pledged US support to Afghanistan but said Afghans must decide their own future.