The Queensland Government says almost the entire Wicked Campervans fleet has been taken off the state's roads because of safety concerns.

The hire company voluntarily decommissioned 77 of its 86 brightly-painted vans when asked for the vehicles to undergo safety tests.

A further five vans submitted for testing were taken off the road by transport officials, leaving just four still in action.

Acting Premier Paul Lucas says he has written to other governments to warn them about the problem.

"I am relieved that we have been able to investigate and act here in Queensland before a terrible tragedy occurred," Mr Lucas said.

"We have seen the incidents involving four-wheel drives on Fraser Island and the Government has taken measures there to try and protect visitors to our state."

Mr Lucas says the December investigation took place after random compliance checks at Wicked Campers outlets in August and October in Cairns.

The results prompted inspectors to investigate the company on a state-wide basis.

Mechanical faults included structural rust, defective seating, oil leaks and severe accident damage.

- ABC/AAP