A group of Indigenous Tasmanians has used a visit by federal Treasurer Peter Costello to protest against plans to invite private law firms to tender for Aboriginal legal services.

More than 40 people waving anti-Government placards heckled Mr Costello as he arrived at Hobart's Wrest Point Casino last night to attend an anniversary dinner for Tasmanian Senator Eric Abetz.

Tasmanian Aboriginal Centre spokeswoman Heather Sculthorpe says the protesters wanted Mr Costello to explain why the Aboriginal Legal Service is to be replaced.

Ms Sculthorpe says programs run by the service in Tasmania have reduced Aboriginal imprisonment rates.

"We think that they're trying to get rid of Aboriginal dissent," she said.

"They're trying to get rid of loud voices for Aboriginal rights and Aboriginal justice and they're taking us back to the '70s when legal services started in this country."