(CNN) Afghan forces holding out against a Taliban assault on the district of Sangin are reportedly running out of weapons and supplies, and there have been no reinforcements despite pleas for help to the central government in Kabul.

Sangin is a key district in Afghanistan's southern Helmand province.

The Taliban took over the entire district except for the police chief's compound and another compound, where a battalion of the Afghan National Army is based, a police official said.

He said that officers were running out of ammunition and food after several days of holding off the Taliban, but no help had reached them yet.

Afghan officials have not responded to repeated calls from CNN to explain the situation.

Afghan CEO Abdullah Abdullah said Monday that the government was working to relieve the forces and repel the Taliban. Meanwhile Afghan President Ashraf Ghani was in transit on a previously scheduled trip to Azerbaijan.

British troops deployed to Helmand

A small contingent of British troops was sent to Helmand over the weekend to provide support to embattled Afghan forces in the province.

The troops, the British Ministry of Defence said in a statement, were "part of the UK's ongoing contribution to NATO's Resolute Support Mission ," the training, advisory, assistance and counterterror mission in Afghanistan. They were deployed to Camp Shorabak, on the site of Camp Bastion, the former British Army headquarters in Afghanistan, the ministry said.

"These personnel are part of a larger NATO team, which is providing advice to the Afghan National Army. They are not deployed in a combat role and will not deploy outside the camp," the statement said.

December marks one year since NATO handed over security operations to the Afghans. Before that, British and American forces struggled for years to hold on to Sangin.

Stuart Gordon, a Helmand expert at the Chatham House think tank, told Britain's Press Association news agency that Sangin held a special significance to the British as more than 100 British troops had been killed there.

"Sangin became fairly totemic for the British because of the number of soldiers lost," he said.

Opium center

A fertile region that is a key location in Afghanistan's poppy trade, Sangin lies in the south of the country in an area that has traditionally been a Taliban heartland.

"It was significant because of the routes it controlled and it was a very significant part of the resourcing of the political economy of Helmand, because it is a major center of drugs processing and drugs shipping," said Gordon.

It was strategically important because it linked Lashkar Gah, the Helmand capital, to districts in the north, he said.

If the Taliban gained control of Sangin, they would control supply routes to the districts, and valuable influence over neighboring provinces, he said.

"If Sangin falls, much of the north of Helmand is very much under Taliban control," he said.

"This is probably the worst of the scenarios that the British had in 2013 and 2014."

Photos: The Taliban Photos: The Taliban The Taliban, a Sunni Islamist organization operating primarily in Afghanistan and Pakistan, was formed in 1994. It was led by Mullah Mohammed Omar, a veteran of the Afghan mujahedeen that fought invading Soviets from 1979-1989. Omar, seen here in an undated video image, died in April 2013 , according to a representative for Afghan President Ashraf Ghani. Hide Caption 1 of 16 Photos: The Taliban In this image taken off television by BBC Newsnight, Omar -- fourth from left -- attends a rally with Taliban troops before their victorious assault on Afghanistan's capital, Kabul, in 1996. The Taliban's aim is to impose its interpretation of Islamic law on Afghanistan and remove foreign influence from the country. Most of its members are Pashtun, the largest ethnic group in Afghanistan. Hide Caption 2 of 16 Photos: The Taliban Tanks manned by Taliban fighters are decorated with flowers in front of the presidential palace in Kabul on September 27, 1996. Hide Caption 3 of 16 Photos: The Taliban Taliban soldiers in Russian-made tanks fire on the forces of former Afghan defense minister Ahmad Shah Massood in October 1996. Hide Caption 4 of 16 Photos: The Taliban Afghan women in Kabul are covered head to toe in traditional burqas on October 16, 1996. After taking over Kabul, the ruling Taliban imposed strict Islamic laws on the Afghan people. Television, music and non-Islamic holidays were banned. Women were not allowed to attend school or work outside the home, and they were forbidden to travel alone. Hide Caption 5 of 16 Photos: The Taliban Three women hitch a ride on the back of a donkey cart as they pass by the ruins of Kabul's former commercial district in November 1996. Hide Caption 6 of 16 Photos: The Taliban This is an undated image believed to show the Taliban's former leader, Mullah Mohammed Omar. In 1997, the Taliban issued an edict renaming Afghanistan the Islamic Emirate of Afghanistan. The country was only officially recognized by three countries: Pakistan, Saudi Arabia and the United Arab Emirates. Hide Caption 7 of 16 Photos: The Taliban In 1997, Omar forged a relationship with al Qaeda leader Osama bin Laden, pictured. Bin Laden then moved his base of operations to Kandahar, Afghanistan. Hide Caption 8 of 16 Photos: The Taliban In March 2001, Taliban soldiers stand at the base of the mountain alcove where a Buddha statue once stood 170 feet high in Bamiyan, Afghanistan. The Taliban destroyed two 1,500-year-old Buddha figures in the town, saying they were idols that violated Islam. Hide Caption 9 of 16 Photos: The Taliban After the 9/11 attacks, the United States conducted military strikes against al Qaeda training camps and military installations of the Taliban regime. In this long-exposure photo, a U.S. Navy fighter jet takes off from the deck of the USS Enterprise on October 7, 2001. Hide Caption 10 of 16 Photos: The Taliban An Afghan anti-Taliban fighter pops up from his tank to spot a U.S. warplane bombing al Qaeda fighters in the Tora Bora region of Afghanistan on December 10, 2001. After massive U.S. bombardment as a part of Operation Enduring Freedom, the Taliban lost Afghanistan to U.S. and Northern Alliance forces. Hide Caption 11 of 16 Photos: The Taliban Afghans look into Omar's bedroom as they go through his compound on the outskirts of Kandahar on December 11, 2001. Hide Caption 12 of 16 Photos: The Taliban In April 2011, hundreds of prisoners escaped from a prison in Kandahar by crawling through a tunnel. The Taliban took responsibility for the escape. This picture shows a general view of the prison, top center, and the house, bottom right, from which Taliban militiamen dug the tunnel leading to the prison. Hide Caption 13 of 16 Photos: The Taliban Security guards stand outside the new Taliban political office in Doha, Qatar, before its official opening in June 2013. The Taliban announced that they hoped to improve relations with other countries, head toward a peaceful solution to the Afghanistan occupation and establish an independent Islamic system in the country. Hide Caption 14 of 16 Photos: The Taliban Zafar Hashemi, deputy spokesman for Afghan President Ashraf Ghani, speaks during a news conference on July 29, when the news of Omar's death was announced. Hide Caption 15 of 16 Photos: The Taliban Mullah Akhtar Mohammad Mansour became the leader of the Taliban after Omar's death. Mansour was killed in an airstrike in Pakistan on Saturday, May 21, 2016 Hide Caption 16 of 16

Facebook plea

Mohammad Jan Rasolyaar, deputy governor of Helmand province, took an unusual step over the weekend by posting an open letter to Ghani on Facebook asking for help.

He warned that all of Helmand could fall to the Taliban if the President didn't take action.

Rasolyaar mentioned Sangin district in his message, saying its main bazaar and the government office were under heavy attack by the Taliban. During the recent intense fighting in Sangin and Greshk districts, 90 Afghan security forces had been killed, he said.

Omar Hamid, head of Asia-Pacific country risk at IHS, told CNN that in Sangin, and before that in Kunduz , the Afghan government forces struggled to put up a fight against the Taliban without foreign backup.

"The problem is where the Afghan forces have to fend for themselves," he said.

"They're fine as long as they're being assisted and they're being provided air cover and things like that by Western forces. But it's when they're left to their own devices that they seem to struggle."