THE credibility of expert witnesses in native title claims came under renewed attack yesterday after the National Native Title Tribunal revealed that it discounts the evidence of anthropologists who are too close to Aboriginal groups.

Tribunal president Graeme Neate said it had criticised some anthropologists for conducting themselves as advocates for Aborigines instead of impartial experts.

"That means the court ultimately gives less weight to their evidence," he said.

Mr Neate said anthropologists and historians had a pivotal role in native title claims, but the pool of experts was small and of "variable quality".

And because anthropologists frequently had long-term relationships with particular groups of Aborigines, he said, their ability to give objective evidence was sometimes open to attack.

Mr Neate's criticism comes after Tasmanian academic Michael Connor attacked the High Court for accepting what he said was a mistaken view of history in the Mabo native title judgment.

The Mabo judgment relies in part on the work of historian Henry Reynolds, whose work has been criticised in Dr Connor's book The Invention of Terra Nullius and in Keith Windshuttle's book The Fabrication of Aboriginal History.

Mr Neate said the tribunal had long been concerned about problems with the credibility of some expert witnesses in native title cases.

But it was dealing with the problem by giving less weight to those witnesses who viewed themselves as advocates for native title claimants.