Six Canadian soldiers were killed by a roadside bomb in Afghanistan on Wednesday, a senior military official said.

The six men and a local Afghan interpreter died when their armored vehicle hit the device about 13 miles southwest of Kandahar. The blast occurred as the troops were returning in a convoy of 12 vehicles from a joint operation with the Afghan national army.

"Clearly, they have managed to kill six great young Canadians today which is an absolute tragedy," Brigadier-General Tim Grant told a televised news conference in Kandahar.

Canada's 2,600-strong mission in Afghanistan is located in Kandahar.

It was the single deadliest attack involving Canadian troops in Afghanistan since six soldiers were killed by a roadside bomb in early April.

So far 66 Canadian soldiers have died since Canadian troops were sent Afghanistan in 2002 to help fight Taliban militants.