The centre of another district in the southern Afghan province of Helmand has fallen to the Taliban, officials say.

The militants are reported to have taken over the police headquarters in Sangin, with fighting continuing in other parts of the district.

Earlier, the deputy governor of Helmand complained of a lack of government support in an open letter on Facebook to President Ashraf Ghani.

Mohammad Jan Rasoulyar warned that the province could fall to the Taliban.

He said at least 90 soldiers had been killed in the latest fighting and claimed Mr Ghani's entourage was not telling him the reality of the situation.

"Helmand will collapse to the enemies and it's not like Kunduz, where we could launch an operation from the airport to retake it. That is just impossible and a dream," he said.

Mr Rasoulyar used the Facebook post to appeal to the president for direct intervention in the province.

"Be quick and act on this! Protect Helmand from this life and death situation and distance yourself from the circle of those lawyers who tell you everything is OK and the situation is normal," he wrote.

In recent months, Taliban insurgents have launched multiple offensives, stretching the Afghan army, which is short of reinforcements, fuel and ammunition.

The fact that a senior Afghan official is addressing the president on Facebook reflects significant internal divisions within the administration, says the BBC's World Service South Asia Editor Ethirajan Anbarasan.