TWO Australian women were killed when their tour group's truck veered off a road and overturned in Namibia.

Jarrah Young, 27, of Queensland, and Sarah Penberthy, a 22-year-old Brisbane nurse originally from Inverell in NSW, were killed on Wednesday near the city of Usakos.

Ms Penberthy was on a four-month African holiday after graduating from the Queensland University of Technology.

Her friends and relatives posted condolences and memories on Ms Penberthy's Facebook page: ''So Sad. You took life with 2 hands and gave it hell. RIP Sarie,'' wrote her cousin, Christine Roberts. A friend wrote: ''You were the perfect partner in crime and a fantastic friend. The memories I have are the kind that last a lifetime.''

Three other Australians sustained minor injuries in the accident but were later discharged from a local hospital.

The women were travelling to the city of Swakopmund with 10 other people. The cause of the accident is unknown.

A Department of Foreign Affairs spokeswoman said an Australian consular official had travelled to Namibia to assist the injured Australians and the families of the deceased.