A senior Army officer defended the role of British troops in Afghanistan yesterday, saying that he was cautiously optimistic that they could defeat the Taleban.

Brigadier Andrew Mackay, the commander of 52 Infantry Brigade who recently headed Taskforce Helmand, also claimed that life was now much safer than it was two years ago in most of southern Afghanistan.

Brigadier Mackay's comments came a day after Air Chief Marshal Sir Jock Stirrup, the Chief of the Defence Staff, gave fresh warning of the military being overstretched, and said they could not continue to fight in both Iraq and Afghanistan.

Despite Sir Jock's intervention, Brigadier Mackay, who commanded more than 6,000 British soldiers in Helmand and has also served in Northern Ireland, Bosnia, Kosovo and Iraq, insisted that British troops were winning the battle for hearts and minds in southern Afghanistan.

He said: “I'm cautiously optimistic that we will get this right - and I say cautiously optimistic with a caveat, because there is an awful lot that can yet go wrong in Afghanistan as we fight this very complex counter-insurgency.

“At the tactical level - the counter insurgency in Helmand - there is no doubt that we are slowly succeeding. Of course, it is very difficult to see but if you take the mantra that ‘the population is the prize', the majority of the population in Helmand from Lashkar Gah, Gereshk, Sangin and Musa Qaleh, the four major urban areas, now enjoy a degree of security that was unthinkable before we moved into Helmand two years ago.”

Fighting the Taleban was more complex than any operation with which he had been involved during the long military campaign in Northern Ireland, he said.“It is the degree and level of insurgency we are fighting,” he said. “It is an enemy that does not care about collateral damage; it is an enemy that does not care about innocent civilians; it is an enemy that is living cheek-by-jowl with the drug trade.

“The complexity of that is something our soldiers have to deal with day-in day-out, but because of their training they are well-equipped to do that.”

Brigadier Mackay was speaking at a presentation in Glasgow to raise funds for Erskine, a charity that provides nursing and medical care for veterans.

The event was overshadowed by news of two more fatalities in Afghanistan, bringing to 108 the number of British servicemen and women who have lost their lives there since 2001.

Brigadier Mackay would not comment directly on the latest deaths but said that the risk was part of the job. “If I am honest I had no sense of what the losses might look like in raw numbers - 24 died on our tour, and there were quite a lot more seriously injured.

“But we are trained and geared up for casualties. Each one when it comes along is hard, but it doesn't deter us.”

While Brigadier Mackay was confident that troops were making a difference on the ground, he said that more work must be done by the governments of Afghanistan and Pakistan - where many Taleban leaders are based - to combat the insurgency.

“There is no doubt that we've got to do better at the higher level,” he said. “What we're doing at the ground level and at the high level at some point meet.”

He also agreed with Sir Jock that the Army could be involved in Afghanistan for decades.

“It is very hard for me to give a figure,” he said. “The British Ambassador has talked about this being a marathon, not a sprint; many senior people have talked about this being five, ten, fifteen years - that is the kind of time frame we are looking at. You don't resolve counter-insurgencies in a couple of years.”

Jim Scott, the chairman of Erskine, said he was grateful to the Brigadier for supporting the charity. He added: “We really appreciate the efforts not just of the forces here today but all of our troops in Iraq and Afghanistan.”

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