LASHKAR GAH, Afghanistan: NATO forces are back helping Afghan troops repel Taliban insurgents from the strategic opium-growing town of Musa Qala in Helmand province, where in 2007 British and U.S. soldiers waged one of the emblematic battles of the war.

U.S. aircraft carried out three strikes over the weekend after the Taliban advanced on the town, seizing weapons and vehicles from Afghan soldiers they captured in an offensive aimed at expanding the militants` grip on Helmand.

The Taliban have sought to secure territory in the north and south this summer but, despite some gains and a spike in attacks in the capital Kabul, they struggle to hold ground, even though most foreign coalition forces withdrew from Afghanistan in 2014.

Brian Tribus, spokesman for U.S. forces in Afghanistan, said air strikes were called in against "individuals threatening" both Afghan and NATO coalition troops. He did not give details. A spokesman for the Afghan army in the area said 37 militants were killed in the strikes, and another 40 wounded.

The district governor in Musa Qala called on Monday for more military support to stop the town falling back into the hands of the Taliban, who occupied it for months until a 2007 battle that involved thousands of troops.

Success in that battle was hailed by then British Prime Minister Gordon Brown and was a morale boost for the fledgling Afghan army, which fought its first major battle in Musa Qala.

British forces have suffered more fatalities in Helmand than any other Afghan region, losing more than 400 soldiers from the U.S. invasion of the country that ended the Taliban`s five-year, radical Islamist rule through last year. More than 350 U.S. Marines have also died there.

The Marines operated a base in Musa Qala until 2013, although the area was never completely free of militants drawn in part to the district`s status as one of Afghanistan`s most lucrative opium-producing centres.

"The Taliban are getting prepared to attack us from three directions tonight. If we don`t get support soon the district will collapse in Taliban hands," governor Mohammad Sharif said.

Sabiq Jihadmal, a Twitter user with links to the insurgents, said they had seized several army posts on Sunday night. Over the weekend, a large army camp a few miles from town was overrun, and 25 soldiers were captured.

"They are missing now. The Taliban have their weapons and vehicles now and are fighting us with those heavy weapons," Sharif said.

Helmand police said it sent reinforcements to the district on Monday and would defend it. A source in provincial capital Lashkar Gah, however, said the Taliban was also sending more fighters.

Since the Taliban were toppled from power by the U.S. invasion prompted by the Sept. 11 al Qaeda attacks on New York and Washington, they have waged a guerrilla war to regain power in Kabul.

One Helmand district bordering Musa Qala is already totally controlled by the Taliban and they dominate several other neighbouring districts. One of those, Naw Zad, has been under alternate Taliban and Afghan army control for several weeks.

Another district, Tajiki, is home to Afghanistan`s largest hydroelectric dam. The dam generates electricity to Helmand and Kandahar but on Monday, because of the fighting, supplies were cut, a frequent occurrence.