British military personnel have been deployed to Afghanistan's Helmand province as reports suggest the Taliban is close to overrunning Sangin town.
The Ministry of Defence said a small number of personnel had been sent to Camp Shorabak in Helmand in an "advisory role", the BBC reported.
They will not be in combat and are part of a larger Nato team, the MoD said.
UK combat operations in Afghanistan ended last year, but around 450 troops remain in mentoring and support roles.
In the east, a Taliban suicide bombing near Bagram killed six US soldiers on Monday in one of the deadliest attacks on foreign forces in Afghanistan this year.
Helmand's governor, Mirza Khan Rahimi, insisted the authorities were still in control of Sangin, in Helmand province, but his own deputy said the town had been overrun by Taliban militants.
The police headquarters reportedly remains under siege on Tuesday morning after a Taliban attack.
A spokeswoman for the MoD said the troops were being deployed as part of the UK's "ongoing contribution" to Nato's Resolute Support mission.
"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," she added.
Helmand province is familiar to thousands of British service personnel; the town of Sangin having a special symbolic significance. More than 100 British soldiers were killed in the struggle for Sangin before responsibility for the area was handed over to the Americans in 2010.