Britain's offensive against the Taliban is gaining ground despite the losses of recent days, Gordon Brown said yesterday as he tried to rally faltering public support for the campaign in Afghanistan.

The Prime Minister described the mission as a “patriotic duty” to keep the streets of Britain safe from the threat of terrorist attack.

He paid tribute to the “sacrifice” of the 15 troops who have died since the start of the month, in the bloodiest fighting the Army has seen in the current campaign.

The Ministry of Defence named six more of the dead — including the five members of Ulster-based 2nd Battalion The Rifles who were killed on Friday during a foot patrol near the town of Sangin in central Helmand.

Also named was Corporal Lee Scott (26), of the 2nd Royal Tank Regiment who died in an explosion near Nad-e-Ali in Helmand on the same day.

Two soldiers killed on Thursday were named as Rifleman Daniel Hume (22), of 4th Battalion The Rifles, and Private John Brackpool (27), of Prince of Wales' Company, 1st Battalion Welsh Guards.

US President Barack Obama said his “heart went out” to the families of the troops who had been killed as he praised the British contribution to the international effort in Afghanistan.

“Great Britain has played an extraordinary role in this coalition,” he told Sky News. “The contribution of the British is critical.”

In an interview with the British Forces Broadcasting Service, Mr Brown acknowledged it was proving to be a “difficult summer” for the troops.

“These sacrifices that have hurt so many families in our country are ones that the whole of Britain will want to acknowledge,” he said.

He said that he had been assured in a lengthy briefing by commanders that the Operation Panther's Claw offensive to drive the Taliban from central Helmand province was making “considerable progress”.

“I think the operation we are engaged with is showing signs of success. Our troops are making progress as they attempt to make the area safe,” he said.

“The reports I have show that despite the loss of life, and it is tragic and very, very sad indeed, our forces are doing a magnificent job moving forward.”

His comments came as Conservative former defence secretary Lord King of Bridgwater became the latest senior figure to criticise the conduct of the campaign, saying “serious political mistakes” had been made by the government.

There had never been enough troops on the ground, he said, and the force was suffering from a “critical shortage” of helicopters.

“What matters now is this crunch time. We are in this critical offensive at the present time which, I think, will determine the outcome of the whole Afghanistan campaign.

“They must have the resources to do the job,” he said.

Former Liberal Democrat leader Sir Menzies Campbell urged Mr Brown to bring the political parties together to formulate an agreed strategy for Afghanistan.

“Political uncertainties run the risk of affecting the morale of troops on the ground and their families. The Prime Minister must now engage with all parties in the House of Commons,” he said.

Mr Brown acknowledged that there was public concern about the campaign, but he insisted there was a “clear strategy” to remove the terrorist networks from Afghanistan and Pakistan in order to protect the streets of Britain.

“This is a patriotic duty,” he said. “Of course people want to know if the action we are taking is the right action.

“It comes back to terrorism on the streets of Britain.

“If we were to allow the Taliban back in power in Afghanistan and al-Qaeda then to have the freedom of manoeuvre, as it had before 2001, then we would be less safe as a country.

“There is a line of terror — what you might call a chain of terror — that links what's happening in Afghanistan and Pakistan to the streets of Britain.”