KANDAHAR, Afghanistan -- Taliban gunmen have overrun a strategic district in the southern province of Helmand, delivering a serious blow to government forces, Afghan officials said on Monday.
Fierce fighting in the Sangin district was continuing after the insurgents took control late Sunday, said Mohammad Jan Rasulyar, Helmand's deputy governor.
Only Afghan army facilities in the district had not been taken by the insurgents, he said. Casualties among Afghan security forces were high, he added, though he gave no figures.
Afghanistan's Chief Executive Abdullah Abdullah met with security advisers early Monday and urged "immediate action," his deputy spokesman Javid Faisal said. He said Afghan forces had launched a counter-offensive to retake control of the district.
Rasulyar on Sunday took the unusual step of using his Facebook page to warn President Ashraf Ghani that the entire province of Helmand was in danger of falling if central authorities failed to send help.
More than 90 members of the Afghan security forces died fighting in recent days, with hundreds killed in the past six months, he said in his open letter to Ghani.
Helmand is an important Taliban base as it produces most of the world's opium, a crop that helps fund the insurgency.
Sangin district has bounced in and out of Taliban control for some years, and fighting there has produced high casualties among both Afghan and international forces. British forces in particular saw intensive fighting there at the height of the war in 2006 and 2007. Britain lost more than 450 troops during its combat mission in Afghanistan, more than 100 of them in Sangin.
The head of Helmand's provincial council, Muhammad Kareem Atal, said that 28 members of the Afghan security forces -- usually a reference to army and police who also fight on the front lines across the country -- were killed fighting on Sunday. Another 15 were critically wounded, he said.
"Around 65 percent of Helmand is now under Taliban control," Atal said. "In every district either we are stepping back or we are handing territory over to Taliban, but still, until now, no serious action has been taken," he said, echoing Rasulyar's plea to the central authorities for help.
Important districts across Helmand province, including Nad Ali, Kajaki, Musa Qala, Naw Zad, Gereshk and Garmser, have all been threatened by Taliban takeover in recent months. Insurgents are also believed to be dug in on the outskirts of the provincial capital, Lashkar Gah.
Taliban fighters, sometimes working with other insurgent groups like the Islamic Movement of Uzbekistan, have managed to overrun many districts across the country this year, as well as staging a three-day takeover of the major northern city of Kunduz. They rarely hold territory for more than a few hours or days, but the impact on the morale of Afghan forces is substantial.
Atal said more than 2,000 members of the security forces had been killed fighting in Helmand in 2015.
He said a major reason "that our forces are losing" was that many soldiers and police were deserting their posts in the face of the Taliban onslaught.
"There is a big difference between the number of both soldiers and police recorded as on duty, and the real number," he said, saying the official record was stuffed with "ghost police and soldiers."
In his open letter to Ghani on Facebook, Rasulyar detailed problems with logistics and evacuation of wounded personnel, and noted that foreign forces only observe, according to the "train, assist, advise" mandate adopted by NATO this year, rather than join their Afghan counterparts in combat.
"Your Excellency, Facebook is not the right forum for speaking with you, but as my voice hasn't been heard by you I don't know what else to do. Please save Helmand from tragedy. Ignore those liars who are telling you that Helmand is secure."
The Taliban have spread their insurgency across the country this year, following the withdrawal of international combat forces at the end of 2014. This has stretched government resources, leading to high casualties and low morale.
The Pentagon released a report last week warning that the security situation in Afghanistan would deteriorate as a "resilient Taliban-led insurgency remains an enduring threat to U.S., coalition, and Afghan forces, as well as to the Afghan people."
The U.S. now has about 9,800 troops in Afghanistan, some of which are involved in counterterrorism missions. With NATO contributions, there are about 13,000 foreign troops in Afghanistan.
Associated Press writer Humayoon Babur in Kabul, Afghanistan, contributed to this story.