The Taliban has taken control of a strategic district in the southern Afghan province of Helmand.

Mohammad Jan Rasoolyar, deputy governor of Helmand, said on December 21 that Taliban fighters had captured nearly all of Sangin district after days of fighting.

According to Rasoolyar, only Afghan National Army facilities in the district have not been taken by the insurgents. Fighting is still ongoing.

In Kabul, Abdullah Abdullah, chief executive of the national-unity government with President Ashraf Ghani, pledged "immediate action" after a meeting with security ministers.

On December 19, Rasoolyar took the unusual step of using Facebook to warn Ghani that Helmand Province was in danger of falling if central authorities failed to send help.

He said more than 90 security troops died fighting in the past month.

Helmand Province is an important Taliban base, as it produces most of the world's opium, a crop that helps fund the insurgency.

Violence has increased sharply across Afghanistan since the U.S.-led military coalition formally ended its combat mission last year.

Based on reporting by AP and RFE/RL's Radio Free Afghanistan