The spokesman for the task force in Helmand, Lieutenant Colonel Nick Richardson, said: "The soldiers are very grateful for that support. It gives us a buoyant and a reassuring feeling."
On Sunday, the Ministry of Defence named six soldiers who were killed in Helmand last Friday.
Five were members of the County Down-based 2nd Battalion The Rifles. They were: Cpl Jonathan Horne, and Riflemen Joseph Murphy, Daniel Simpson, William Aldridge and James Backhouse.
The sixth was Cpl Lee Scott, of the 2nd Royal Tank Regiment.
In the same 24 hours - the bloodiest since the start of operations in Afghanistan in 2001 - Rifleman Daniel Hume, of 4th Battalion The Rifles, and Pte John Brackpool, 1st Battalion Welsh Guards, also died.
Over the weekend, Gordon Brown defended the strategy in Afghanistan and said the government had increased defence spending by more than a billion pounds in the past year.
He said new equipment had already been provided and more, including Merlin helicopters and Ridgeback armoured vehicles, would arrive in the coming months.
But he added: "We must do more and we will do more."
People watching Portsmouth parade: "I don't think our boys should be there"
Speaking to the British Forces Broadcasting Service, Mr Brown insisted the mission in Afghanistan was crucial to the UK's domestic security.
UK troops have spent recent weeks on an offensive - codenamed Panther's Claw - which is designed to increase security ahead of Afghan elections planned for next month.
But the surge has brought a big increase in casualties, with 15 servicemen killed in the first 10 days of the month.
It means 184 service personnel have now died in Afghanistan since 2001, more than the 179 who were killed during the war in Iraq.
The deaths of the three 18-year-olds matches the number previously killed at that age during almost eight years of conflict in Afghanistan.
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