Global ride-share company Uber could be forced to shell out hundreds of millions of dollars if a class action launched by thousands of Australian taxi and hire car drivers is successful.

More than 6000 people have joined the action, covering drivers across Victoria, NSW, Queensland and Western Australia.

The action deals with the period before Uber was legalised in those jurisdictions, and alleges it operated illegally because the company knew its drivers were not properly licensed and accredited when it first entered the market.

"Make no mistake, this will be a landmark case regarding the alleged illegal operations of Uber in Australia and the devastating impact that has had on the lives of hard-working and law-abiding citizens here," Maurice Blackburn's national head of class actions Andrew Watson said.

"It is not acceptable for a business to place itself above the law and operate illegally to the disadvantage of others."

Uber had not received notification of a class action and denied it ever operated illegally.

"If a claim is served ... the claim will be vigorously defended," a spokeswoman said.

Maurice Blackburn's Elizabeth O'Shea said it could be the largest class action in Australian history.

"When you look at some of the value drops in taxi licences and their contraction in income for some of these people around the country and given how many people are likely to be affected, we're definitely talking hundreds of millions of dollars," she told ABC radio.

Lead plaintiff, Melbourne taxi driver Nick Andrianakis, says Uber took away his livelihood.

"My father owned and drove cabs, so it's been an industry and job that's in my blood and that I've loved my whole life - then suddenly that was all taken away because of the impact of Uber's illegal activities," he said.

"I can clearly remember the day it all became too much - I just stopped driving that day and had to go home to be with my wife. It's a shocking thing to think of a life's work being stripped away from you, but this is what's happened to thousands of people nationwide."

The Uber spokeswoman said the company planned to continue "delivering a great service to riders and drivers".

"Over 3.8 million Australians regularly use Uber as a reliable choice to get from A to B and governments across the country have recognised ride-sharing as part of the transport mix," she said.

Costs of the action, filed in the Victorian Supreme Court on Friday, will be underwritten by a third party litigation funder.