NATO is donating millions of dollars' worth of military equipment to Afghanistan, it said on Tuesday, as its forces leave the beleaguered country under the shadow of a resurgent Taliban.

"As we withdraw our forces from the country, we will continue to support Afghanistan, including with equipment to help the Afghan forces better provide for their own security," NATO spokesman Dylan White said in a statement.

So far this year, NATO said, it has given supplies worth $72 million (62 million euros) to the Afghan government to help in its fight against the Taliban, which has seized many rural regions since US-led forces started pulling out in May.

The equipment includes specialist bomb-defusing devices, body armour, combat simulators, firefighting trucks and medical supplies that will go to "treat wounded soldiers on the battlefield," the alliance said.

The announcement came as the 200,000 residents of Lashkar Gah, the main city in Afghanistan's southern Helmand province, were being urged to evacuate under a withering Taliban offensive.

At least 40 civilians have been killed there since the weekend, according to the United Nations.

A massive blast meanwhile rocked Kabul on Tuesday evening, sending a thick plume of smoke into the sky, AFP correspondents reported.

US warplanes have stepped up airstrikes across the country in recent days to try to slow the Taliban advances.

But the last of the US forces are set to leave this month, ending America's longest war.

They are withdrawing under orders from US President Joe Biden, who has said his country has done all it can in Afghanistan after invading two decades ago to wipe out Al-Qaeda extremists held responsible for the September 11, 2001 attacks in the United States.

NATO allies are withdrawing their forces at the same time, although the alliance chief, Jens Stoltenberg, has vowed continued support in terms of financing and training outside of Afghanistan.