Canberra: An elite Australian soldier was shot dead during his seventh tour of duty in Afghanistan, a commander said on Tuesday, raising the number of Australian troops killed in the more-than-decade-long war to 33.

The 40-year-old veteran of the Special Air Service Regiment was killed in the Chora Valley in Uruzgan province on Monday during an operation involving Australian and Afghan troops targeting an insurgent commander, Australian Defence Force Chief Lt Gen David Hurley said.

The soldier was evacuated with a chest wound to the military hospital at the Australian base at Tarin Kowt but could not be resuscitated, Hurley said. His name has not been made public at his family’s request.

Hurley said it was “probably unusual” that a soldier had served seven tours, but he added that he does not believe soldiers are not being asked to do too much.

“I’m confident that the [psychological] management processes are in place ... and all of them are volunteers to go back to serve in Afghanistan,” he told reporters.

“But it’s an issue we need to keep a sharp eye on,” he added.

Neil James, executive director of the Australian Defence Association, an influential security think-tank, said it’s “unusual, but not that unusual” for an SAS soldier to have so many Afghan tours.

“The real problem is the country is expecting a very small part of the national family to bear the burden of its wars, and the association doesn’t think that’s right,” he added.

The Australian Defence Force needs to share the fighting load more broadly among its 58,000 troops, he said.

Australia has 1,550 troops in Afghanistan and is the largest military contributor to the US-led alliance outside Nato. Australia also provides the third-largest force of special operations troops after the United States and Britain.

Australia’s elite Special Operations Task Force in Afghanistan, which numbers about 300, draws from the SAS and two commando regiments that total fewer than 1,600 troops. The duration of SAS tours are flexible, but they typically extend beyond six months.

After taking command of Australia’s military a year ago, Hurley said the death of a decorated commando on his fifth tour of duty in Afghanistan raised the question of whether Australia was asking too much of its elite soldiers. He then took advice on the subject from regiment commanders.

The soldier killed on Monday enlisted in the army in 1990 and joined Australia’s most elite regiment in 1995.

Prime Minister Julia Gillard has said the Australian special operations force could remain in Afghanistan after the Afghan military takes charge of their nation’s security in 2014.

She described the latest death as a “dreadful blow.”

“This tragic incident is part of what we are doing in Afghanistan because that mission is so important to our Australian nation,” she said.