The Taliban has launched a coordinated assault on the city of Kunduz in Afghanistan, attacking from four directions and entering the city itself, officials said.

Sheer Ali Kamal, commander of the 808 Tandar police zone in Kunduz, said on Monday that the attack began at around midnight (1930 GMT Sunday) and fighting was still going on in and around the city.

"We are putting all our efforts together to push them back," he said.

Military helicopters were flying overhead and gunfire could be heard in the city.

Al Jazeera's Jennifer Glasse, reporting from the capital, Kabul, said: "It will be difficult to dislodge them as we understand that the Taliban have taken positions inside civilian homes. Police and security forces are having difficulty distinguishing where exactly the fire is coming from."

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Kunduz, which fell briefly to the Taliban a year ago, has seen repeated bouts of heavy fighting and was previously seriously threatened in April, July and August.

"We are hearing from government officials that the Taliban actually said they entered Kunduz city because they were unhappy with Afghan Special Forces activities in two different districts in Kunduz, where Afghan forces have been fighting with the armed group," Glasse said.

A Taliban spokesman, Zabihullah Mujahid, had earlier announced the attack on Twitter. 

He said the Nawabad area, and four checkpoints there, had been captured and several soldiers had been killed in a statement that was not immediately possible to verify.

A Reuters news agency journalist saw at least five Taliban fighters armed with AK-47 assault rifles, machine guns and rocket-propelled grenades in the city.

'A show of force'

The attack came as the Taliban stepped up operations in different parts of Afghanistan, including the strategic southern province of Helmand, where they have been threatening the provincial capital of Lashkar Gah.

Glasse said that Taliban had also attacked Nawa district in Helmand province, killing its police chief.

"This does seem like a show of force by the Taliban," she said.

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The fall of Kunduz last year was one of the most serious blows suffered by the Western-backed government in Kabul since the withdrawal of most foreign troops at the end of 2014.

A Taliban raid on Tarin Kot, the provincial capital of Uruzgan in the south, on September 8 also sparked fears of another collapse.

Monday's attack, a day before the start of a major donor conference in Brussels, underlines the precarious security situation in Afghanistan, where government forces are estimated to have control over no more than two thirds of the country.

At the conference, Afghanistan's foreign donors are expected to approve maintaining billions of dollars in funding for the government over the next four years.

Afghan security forces retook control of Aachin district of Kunduz after it was briefly taken over by the Taliban in August [EPA]

Source: Al Jazeera News And Agencies