The toll of British lives lost in Afghanistan surpassed that of the Falklands war last night with news of the 256th fatality since military action began in 2001.

Earlier the deaths of two members of The Royal Scots Borders, 1st Battalion The Royal Regiment of Scotland, had taken the number of fatalities level with that of the south Atlantic conflict 28 years ago.

Comrades said the latest death, of a soldier from 36 Engineer Regiment, happened as he led a team clearing roads of bombs in the Nad-e-Ali District, in central Helmand province.

The other two soldiers were on foot patrol near Sangin, in northern Helmand, when they were killed by an explosion on Sunday night.

As Lieutenant Colonel David Wakefield, spokesman for Task Force Helmand, paid tribute to the “bravery and fortitude” of the latest casualties, Defence Secretary Bob Ainsworth warned the death toll was likely to rise as a result of Operation Moshtarak, a major offensive due to begin in the coming days.

He said: “We have seen an intense, hard and bloody period in Afghanistan but, as we prepare to consolidate our progress with the launch of Operation Moshtarak, it is imperative that we hold our resolve. The national security of the UK and the safety of its citizens depends on that.

“Our presence in Afghanistan is vital in preventing it from once again becoming a haven for terrorists who would seek to threaten the UK.”

The Ministry of Defence would not confirm whether the soldier from the Engineer Regiment was involved in Operation Moshtarak.

L/Col Wakefield added: “He was leading a team conducting route clearance operations at the time, making the way ahead safe for others to follow.”

The Falklands war, sparked after Argentina invaded the remote British colony, resulted in the deaths of 255 British service personnel, 655 Argentinians and three Falkland islanders in just 74 days.

Falklands veteran Simon Weston, who suffered severe burns when his ship the Sir Galahad was bombed in the conflict, said: “The Falklands was a more conventional conflict – it was two armies wearing uniforms engaged against each other.

“The Argentines acted as we did, in a honourable way.

“Afghanistan is very different. Our boys and girls are fighting people using essentially guerrilla tactics.”

But Mr Weston insisted troops should not be pulled out of Afghanistan if it would mean a return to the Taliban regime.

“We can’t let the Taliban back in to conduct themselves the way they did before,” he said.