Evidence of what could be Australia's earliest human occupation has been found on the fringe of desert in the country's remote northwest, according to archaeologists.

Peter Veth, of the Australian National University, said an artefact dated at between 45,000 and 50,000 years old found near the shores of Lake Gregory could be the start of a 25-year study into Australia's first humans.

"This is the first evidence of human activity ... in the arid northwest of the continent which can be dated to a time before the last great Ice Age," he said in a statement.

It was likely to be of "the same order of antiquity" as the oldest human remains found in the country, discovered in the country's eastern state of New South Wales in 1969 and dated at around 40,000 years old, he said.

"It's just important because it's an early site full stop," remarked Dr Veth of the discovery, a piece of stone from which flakes have been struck to form tools.

"To get an early date there and then to get evidence of repeat occupation is highly significant."

Dr Veth said the archaeologists had been extremely conservative in their dating of the artefact, which was found in 2008, adding that the site was likely to be a rich source of data in the years to come.