Taliban militants captured a sixth provincial Afghan capital on Monday, a lawmaker said, after they ousted Afghan security forces from border towns and trade routes as US-led foreign forces pull out.

The Taliban, fighting to reimpose strict Islamic law after their 2001 ouster, have stepped up their campaign to defeat the government as foreign forces withdraw after 20 years of war.

On Monday, they took Aybak, capital of the northern province of Samangan.

“Right now the Taliban are fighting with Afghan forces to capture the police headquarters and compound of the provincial governor,” said Ziauddin Zia, a lawmaker in Aybak.

“Several parts of the capital have fallen to the Taliban.”

The insurgents took three provincial capitals over the weekend — Zaranj in the southern province of Nimroz, Sar-e-Pul, in the northern province of the same name, and Taloqan, in northeastern Takhar province.

They had already taken the northern provincial capital of Kunduz and Lashkar Gah, capital of Helmand province.

The Taliban gains have sparked recriminations over the withdrawal of foreign forces. British defence secretary Ben Wallace told the Daily Mail that the accord struck last year between the US and the Taliban was a “rotten deal”.

Wallace said his government had asked some Nato allies to keep their troops in Afghanistan once the US troops departed, but failed to garner enough support.

“Some said they were keen, but their parliaments weren’t. It became apparent pretty quickly that without the US as the framework nation it had been, these options were closed off,” Wallace said.

Germany’s defence minister rejected calls for its soldiers to return to Afghanistan after Taliban insurgents took Kunduz where German troops were deployed for a decade.

Afghan commandoes had launched a counter-attack to try to beat back Taliban fighters who overran Kunduz, with residents fleeing the conflict describing the almost constant sound of gunfire and explosions.

A Taliban spokesman warned the US on Sunday against intervening following US air strikes to support beleaguered Afghan government forces. The US has vowed to pull out most troops by the end of the month.

In the west, near the border with Iran, security officials said heavy fighting was under way on the outskirts of Herat. Arif Jalali, head of Herat Zonal Hospital, said 36 people had been killed and 220 wounded over the past 11 days. More than half of the wounded were civilians, and women and children were among the dead.

UNICEF said 20 children were killed and 130 children had been injured in southern Kandahar province in the last 72 hours.

”The atrocities grow higher by the day,” said Hervé Ludovic De Lys, UNICEF's representative in Afghanistan.

In Helmand, a hotbed of Taliban activity, security officials reported a loud explosion in Lashkar Gah on Monday morning.

The insurgents have taken dozens of districts and border crossings in recent months and put pressure on several cities.

U.S. officials, speaking on the condition of anonymity, said that while the military had warned President Joe Biden earlier this year that provincial capitals would fall with a withdrawal of troops, they were still surprised at how quickly some of them were being taken by the Taliban.

The United States carried out less than a dozen strikes over the weekend as the Taliban overran the provincial capitals, in one instance simply destroying equipment.

The U.S. officials said they had little expectation that American air strikes alone could halt the Taliban gains, especially once insurgents entered densely populated cities.

Families flee

In Kunduz, many desperate families, some with young children and pregnant women, abandoned their homes, hoping to reach the relative safety of Kabul, 315 km (200 miles) to the south - a drive that would normally take around ten hours.

Ghulam Rasool, an engineer, was trying to hire a bus to get his family to the capital as the sound of gunfire reverberated through the streets of his hometown.

”We may just be forced to walk till Kabul, but we are not sure if we could be killed on the way ... ground clashes were not just stopping even for 10 minutes,” Rasool told Reuters.

He and several other residents, and a security official, said Afghan commandoes had launched an operation to clear the insurgents from Kunduz.

In Kabul itself, suspected Taliban fighters killed an Afghan radio station manager, government officials said, the latest in a long line of attacks targeting media workers.

Thousands were trying to enter Kabul, even after the city has witnessed attacks in diplomatic districts.

Speaking to Al-Jazeera TV on Sunday, Taliban spokesman Muhammad Naeem Wardak warned the United States against further intervention to support government forces.