Four British soldiers died when their vehicle overturned on the way to investigate an incident at a checkpoint near Gereshk, in Helmand province.
The soldiers, part of a police advisory team, were travelling in a Ridgeback armoured vehicle which rolled off the road and ended up underwater. Enemy action is not thought to have been involved, the Ministry of Defence said.
Three of the four who died yesterday were from 1st Battalion the Mercian Regiment, and one from 1st Battalion the Yorkshire Regiment, who were serving in Nahr-e-Saraj as part of a police advisory team.
Their names have not been released yet at the request of their families.
Lieutenant Colonel James Carr-Smith, spokesman for Task Force Helmand, said: "They were part of a team that was travelling to assist in an incident at a nearby checkpoint when they were killed in a vehicle incident. They will be sorely missed and their actions will not be forgotten. We will remember them".
Seven soldiers have died since the 300th casualty of the conflict was announced on Monday, making it one of the worst weeks in the nine years of the war in Afghanistan.
The deaths took the number of UK troops who have died since operations in Afghanistan began in 2001 to 307.
This includes 18 so far this month, of whom nine have died in the past seven days.
