British forces have been involved in a major operation against the Taliban
A soldier from the 1st Battalion Welsh Guards has been killed in an explosion in southern Afghanistan, the Ministry of Defence has said.
The blast happened in an operation near Gereshk in central Helmand province on Sunday. Next of kin have been informed.
British forces have been involved in a major offensive codenamed Operation Panther's Claw against Taliban strongholds in Afghanistan.
A total of 174 UK service personnel have died in Afghanistan since 2001.
Lt Col Nick Richardson, spokesman for the British military's Task Force Helmand in Afghanistan, said: "It is with extreme sadness that I must report the death of a brave soldier.
"He laid down his life for his country and for the good people of Afghanistan. We grieve for his loss and join with his family and friends to mourn his passing. He will always be remembered."
The death comes after two British soldiers were killed in separate incidents during the same operation on Saturday.
One from 2nd Battalion The Mercian Regiment was killed by a rocket-propelled grenade and the other from The Light Dragoons died in an explosion.
The commanding officer of the Welsh Guards, Lt Col Rupert Thorneloe, was killed on Wednesday alongside Trooper Joshua Hammond when their Viking armoured vehicle was hit by an improvised bomb.
Col Thorneloe was the most senior Army officer to die in action since the Falklands War in 1982.