A soldier from 2nd Battalion, The Parachute Regiment has been killed in an explosion in Afghanistan, the Ministry of Defence has said.
The MoD said he was killed by an improvised explosive device on Monday while on an operation in the Nahr-e Saraj district of Helmand province.
The soldier's next of kin have been informed.
Earlier, the MoD announced that two British soldiers had died in a fire at Camp Bastion in Afghanistan.
The latest death to be announced brings the total number of UK fatalities since operations began in Afghanistan in 2001 to 357.
Lt Col David Eastman, spokesman for Task Force Helmand, said the soldier, who was based in Colchester, in Essex, was on a patrol aimed at reassuring the local population when he was killed.
"Sadly the insurgents have resorted to planting explosives that target innocent civilians and soldiers indiscriminately, without care for the impact that they have or the destruction they cause," he said.
"The soldier gave his life trying to defend against such senseless inhumanity.
"His courage and sacrifice will not be forgotten, and we offer heartfelt condolences to his family and friends. We will remember him."
The MoD said earlier that two soldiers from the Royal Logistic Corps had died in a "domestic" fire at Camp Bastion.
An investigation is now under way into what happened, but the fire is not thought to have been the result of enemy action.
Wing Cdr Martin Tinworth, spokesman for Camp Bastion, said: "Both soldiers were involved in vital support work for the UK forces who continue to bring hope and stability across Afghanistan."
The deaths came after the head of UK forces in Helmand said momentum in Helmand was "shifting".
Brigadier James Chiswell told the BBC: "There's certainly a sense over this winter period that the insurgency is under a lot of pressure, but perhaps more importantly there's certainly a sense of growing local confidence to shake off the insurgency, and indeed to put their trust in the state."
But he said it was too early to judge how successful the past few months had been until fighting during the summer had taken place
Defence Secretary Liam Fox also warned that casualty numbers were "likely to rise" in the spring as insurgent activity increased.