The first troops in an enlarged UK deployment to Afghanistan have begun setting up base.
Royal Marines are protecting engineers working on the base
Several hundred Royal Engineers are building the camp in Lashkar Gar, the capital of southern Helmand province, with protection from 150 Royal Marines.
Around 850 troops are due in place this month, preparing for a deployment of more than 5,000 within six months.
They aim to restore peace and tackle the drugs trade in an area of major Taleban activity and opium production.
Colonel Gordon Messenger, in Helmand, said: "Having the number of troops we will have, operating alongside a similar number of Afghan troops, in the area... will no doubt have a disruptive effect on the narcotics industry, and that will inevitably have... positive implications on the traffic back to the UK."
The Royal Engineers in Helmand are from 39 Regiment, while the Royal Marines are from 42 Commando, whose home base is at Bickleigh, in Devon.
The enlarged British deployment is part of an expanded Nato force in Afghanistan.
Defence Secretary John Reid has said the total number of UK troops in the country at any time will not top 5,700.
This includes a main deployment of 3,300, the 850 conducting preparation work, and about 1,000 troops being sent to the Headquarters Group of the Allied Rapid Reaction Corps.
Mr Reid earlier this week called on the public to be more understanding of the "unprecedented challenges" faced by UK troops in foreign battle zones.
This followed the emergence of a video apparently showing abuse of Iraqi civilians by UK troops two years ago.
BBC defence correspondent Paul Wood has said the Taleban promised a wave of suicide bombings in Afghanistan.
Senior British commanders say the new troops arriving will probably attract an increase in attacks, at least initially.
Lt Col Ged Salzano, commanding officer of 42 Commando, said: "The company group is robust enough to look after itself and protect the engineers.
"Conditions are expected to be tough but 42 Commando are well prepared for the task."
Nato's International Security Assistance Force (Isaf) mission currently numbers about 9,200 troops. It is expected to increase the overall number to about 15,000.
The UK takes control of Nato forces in Afghanistan in May.