Ferocious fighting is taking place in a major Afghan city, amid fears it could be the first provincial capital to fall to the Taliban.

Lashkar Gah in southern Helmand province is under heavy assault from the militants, despite US and Afghan air strikes.

The Taliban are said to have seized a TV station. Thousands of people fleeing rural areas took shelter in buildings.

The UK and US say the Taliban may have committed war crimes.

Hundreds of Afghan reinforcements have been deployed to battle the militants.The Taliban have made rapid advancesin recent months as US forces have withdrawn after 20 years of military operations in the country.

Helmand was the centrepiece of the US and British military campaign, and Taliban gains there would be a blow for the Afghan government.

If Lashkar Gah fell, it would be the first provincial capital won by the Taliban since 2016. It is one of three capitals under attack.

Attempts by the militants to captureKandahar, Afghanistan's second-largest city, have continued after rocket strikes hit its airport on Sunday.

Seizing control of Kandahar would be a hugely symbolic victory for the Taliban, giving them a grip on the south of the country.

In a third besieged city,Herat, in the west, government commandos are battling the insurgents after days of fierce fighting. Government forces have taken back some areas after a UN compound was attacked on Friday.