A suicide bomber has killed four other people and injured 23 in the Afghan town of Gardez, capital of the troubled southern border province of Paktia.
British troops are under constant attack in Helmand
He blew himself up at a checkpoint outside a government building in the town, an eyewitness said.
British troops are engaged in heavy fighting with Taleban militants in the southern province of Helmand.
They say that gunmen are firing from a hospital and that they may be forced to return fire soon.
There have been reports of civilian casualties in Nawzad over the past few days.
According to a statement from the military in Helmand, British forces are under a sustained attack from numerous positions in the Nawzad district government compound they have been defending for 18 days.
In that time, they have been attacked 27 times.
"Our soldiers are showing considerable restraint but we may be required to return fire soon," a spokesman said.
The troops on the ground from the 3rd Para Battle Group are said to be trying to establish whether the hospital was clear of patients or civilians.
One soldier has been injured but not seriously.
Last week, at least three 500-pound (227-kilo) bombs were dropped on Nawzad market and there are claims from local people that a significant number of civilians were killed.
The British spokesman said their use of force had been appropriate, and say they have no evidence of civilian casualties.
Operations by coalition forces in Afghanistan are said to have resulted in the deaths of more than 30 Taleban fighters this weekend, most on Saturday night.
Last week saw heavy clashes in both Helmand and Uruzgan provinces.