London’s black-cab drivers are considering legal action against Uber with potential plans to sue the US ride-hailing service for more than £1bn over their loss of earnings.

The Licensed Taxi Drivers’ Association is consulting lawyers at Mishcon de Reya over a possible claim, according to a report on Sky News, after Uber won a 15-month licence to keep operating in London last month.

Uber’s licence application was initially turned down in September and an appeal judge said that Transport for London had been correct in deciding that Uber was, at that point, not a fit and proper company to hold a licence.

Although it changed its working practices and was later granted a licence, the LTDA claim would relate to the first five years in which Uber operated in the capital. It is expected to argue that 25,000 traditional cab drivers suffered lost earnings of £10,000 a year.

Steve McNamara, the general secretary of the LTDA, said: “We’ve been approached by a number of members to help them explore whether there would be grounds for a potential class action on behalf of all taxi drivers against Uber.

“We are in the very early stages of obtaining legal advice from leading law firm Mishcon de Reya on whether this is a possibility. We’ll continue to do everything we can to support our members and taxi drivers across London by exploring every avenue to ensure they are treated fairly.”

Should the taxi drivers proceed, the legal fight is expected to go ahead in the autumn backed by a litigation funder, with costs from the case potentially running to tens of millions of pounds. A source said litigation funders – which contribute to court costs in return for a share of any payout – would not be involved without a strong chance of success.

According to Uber, about 3.6 million people regularly use its service in London, where it has 45,000 registered drivers.

The company said it was unable to comment on the LTDA’s move without knowing the basis of its potential legal action.

The LTDA previously took unsuccessful court action against Uber, arguing that the ride-hailing service was in effect running off a meter, contrary to its licence.

TfL initially turned down a new London licence for Uber for reasons including contraventions of its licence terms in how it assessed drivers and reported offences to the police.

Since then, Uber said it had made wholesale changes to its practices, to be a “better partner”, including new board oversight in the UK.