A group of London black cab drivers has planned legal action against Uber in an effort to claim "millions of pounds in lost earnings".
The Licensed Taxi Drivers' Association (LTDA) and 11 other organisations hired solicitors to determine if they have a case against the ride-hailing app.
The LTDA claims its drivers, who have average annual earnings of £50,000, have each lost £10,000 a year since Uber began operating in London in 2012.
Uber declined to comment.
It said it would not provide a response as it was "not at all clear what the basis for any legal action would be".
The group, named Cabbie Group Action, also includes members from Unite, United Cabbies Group and London Cab Drivers Club.
It plans to bring a claim in the High Court against Uber for loss of income on the basis that it "has operated unlawfully between 2012-2017".
LTDA said it is working with economists and expect damages could be in excess of £500m.
David Barda, a senior litigation lawyer at Slater and Gordon said the group had "no obvious cause of action" against Uber and that they were "essentially complaining about competition".
Uber was stripped of its London licence last year after Transport for London (TfL) concluded the app was not "fit and proper".
It said it took the decision on the grounds of "public safety and security implications".
But last month, Uber was granted a short-term licence to operate in London after a two-day hearing at Westminster Magistrates' Court found the app had since become "fit and proper".
LTDA's general secretary, Steve McNamara said it was vital its drivers were "recompensed for their losses".
"We recognise that there needs to be a level playing field between minicabs and licensed cabs on London streets but we believe Uber has operated unlawfully, resulting in a loss of earnings for many qualified licensed cab drivers."