KABUL, Afghanistan (AP) -- The Taliban captured a key district center in Afghanistan's southern Helmand province on Thursday while in the country's north, an officer turned his rifle on sleeping colleagues, killing nine policemen, officials said.
The fall of Sangin district, once considered the deadliest battlefield for British and U.S. troops in Afghanistan, comes amid the insurgents' year-long push to expand their footprint in the Taliban heartland of Helmand. The British who took over southern Helmand in 2006 were headquartered at Camp Sebastian, which at its peak was the center for 137 bases in Helmand. Most of Britain's more than 400 military deaths occurred in Helmand province - in Sangin alone, Britain lost 104 soldiers.
Since the withdrawal of foreign NATO combat troops from Afghanistan at the end of 2014, and with only a smaller, U.S.-led advise and training mission left behind, Sangin has been seen as a major tests of whether Afghan security forces can hold off advancing Taliban fighters.
The district's police chief, Mohammad Rasoul, said the Taliban overran Sangin center early on Thursday morning.
Taliban spokesman Qari Yousuf Ahmadi, also issued a statement claiming the Taliban capture of Sangin.
Speaking to The Associated Press over the phone from several kilometers (miles) away from the district center, Rasoul said the district headquarters had been poorly protected and that at the time of the Taliban siege, only eight policemen and 30 Afghan soldiers were on duty.
Afghan security forces were now amassing nearby for a full-scale counter-attack in a bid to retake Sangin, Rasoul added, though he did not say when the assault would occur and how many forces would be involved.
"We are preparing our reinforcements to recapture the district," Rasoul said.
It wasn't immediately clear whether the Afghan military would seek the help of international coalition forces in the area.
NATO spokesman William Salvin said in a statement that Afghan troops remained in Sangin district but had relocated several kilometers (miles) outside the district center. He said the relocation was necessitated because of the extensive damage to the district center by the Taliban.
In Kabul, a lawmaker from Sangin, Mohammad Hashim Alokzai, urged the military to move quickly to retake the district, saying its fall could have devastating consequences for Helmand, where the provincial capital of Lashkar Gah has in the past months also come under constant and heavy attack by the Taliban.
"The seizure of Sangin is a major tactical triumph for the Taliban," Michael Kugelman, senior associate for South Asia at the U.S.-based Wilson Center, said Thursday. The insurgent group "has taken over a major urban space in one of its major stronghold provinces, amplifying the major threat that the group poses to Afghanistan nearly 16 years after it was removed from power."
Sangin is also one of the biggest opium markets in Afghanistan, which saw over 4,800 metric tons produced countrywide in 2016 -- more than all other opium-producing countries combined, according to the United Nations Office on Drugs and Crimes. Efforts at poppy eradication in Afghanistan have been severely restricted because of the insecurity in the southern and eastern regions of the country, where the bulk of the crop is grown.
Opium, which is used to make heroin, is a major source of income for the insurgents and the Taliban levy taxes on opium that moves through its territory.
"It's hard to overestimate the significance of Helmand - it's strategically located near Pakistan, it's a bastion of the opium trade," said Kugelman. "Perhaps the biggest reason why the British focused so much on Sangin is that they had invested so much over the years in trying to stabilize the place - and had suffered many combat deaths in the process."
In northern Kunduz province, police spokesman Mafuz Akbari said the insider attack on Thursday that claimed the lives on nine policemen took place at a security post and that the assailant escaped under the cover of darkness.
Afghanistan has seen a spike in so-called insider attacks. In such incidents, attackers who turn their rifles and kill colleagues usually end up stealing their weapons and fleeing the scene to join insurgents.
Akbari said the assailant had gone over to the Taliban. He also claimed that the attacker and the Taliban gathered the bodies of the dead policemen and set them on fire.
Taliban spokesman Zabiullah Mujahed claimed responsibility for the attack, but denied that a policeman had been involved or that the Taliban had burned the bodies of the policemen.
The conflicting accounts could not be immediately reconciled. The region is remote and not accessible to reporters.
Afghan forces have come under intensified pressure by insurgents in both Helmand and Kunduz.
Gannon reported from Islamabad.