PANJSHIR VALLEY, AFGHANISTAN (AFP) - Atop a craggy mountain that has withstood foreign invaders for decades, anti-Taleban fighters fire a mounted heavy machine gun into a deep valley.

They are members of the National Resistance Front (NRF) - the most prominent Afghan opposition group to emerge since the Taleban captured Kabul nine days ago.

With militia fighters and former government soldiers in its ranks, the NRF has set up machine gun nests, mortars and surveillance posts fortified with sandbags in anticipation of a Taleban assault on their bastion, the Panjshir Valley.

Its fighters, many of them in military camouflage fatigues, patrol the area in US-made Humvees and technicals - pickup trucks with machine guns mounted on the back.

Many carry assault rifles, rocket-propelled grenades and walkie-talkies. Some pose on their vehicles with a dramatic background of snow-covered peaks in the valley, which begins around 80km north of Kabul.

"We are going to rub their faces in the ground," said one fighter at a position in the Panjshir heights, listing past victories against the Taleban.

His comrades then raise their fists and chant "Allah-u Akbar" (God is great).

The strategic valley - populated primarily by ethnic Tajiks - offers natural defence points, with narrow entrances in the shadow of high mountains.

"If Taleban warlords launch an assault, they will of course face staunch resistance from us," Ahmad Massoud, one of the NRF leaders, said in a Washington Post op-ed last week.

He is the son of the late guerilla commander Ahmad Shah Massoud, revered for turning the Panjshir Valley into an anti-Soviet and anti-Taleban bastion.

The defensive preparations are familiar for Panjshir residents who saw Massoud thwart multiple Soviet assaults in the 1980s and Taleban attempts to take the area in the late 1990s.

A spokesman for the NRF told Agence France-Presse at the weekend that it is ready to resist any Taleban aggression but wants to negotiate with the Islamists about an inclusive government.

The Taleban has also said it wants to handle the situation peacefully, but it has bared its teeth by sending hundreds of fighters to the area.

Panjshir was surrounded from three sides, Taleban spokesman Zabihullah Mujahid said on Monday (Aug 23).

Former vice-president Amrullah Saleh, who headed to the valley after the fall of Kabul, said a humanitarian disaster was brewing.

"Talibs aren't allowing food & fuel to get into Andarab valley," he tweeted, referring to an area under Taleban control that abuts Panjshir from the north-west. "Thousands of women & children have fled to mountains."

There have been scattered reports of clashes around Panjshir in recent days, with conflicting claims from both sides that have been impossible to independently verify.

The NRF has said it is ready for battle, but it remains unclear if the force has the supplies and equipment to withstand a long siege by the Taleban.

Ahmad Massoud said in his op-ed that they have arms and ammunition stores, as well as the weapons brought to Panjshir by former Afghan forces.

But he added that without help from the outside world, his fighters would not be able to withstand the Taleban's siege for long.

"We know that our military forces and logistics will not be sufficient," he wrote.

"They will be rapidly depleted unless our friends in the West can find a way to supply us without delay."

Elders from the Panjshir Valley have reportedly been speaking with Taleban officials in the Afghan capital, but there has been no breakthrough yet.