Uber has eased restrictions on black cabs in London with people in the capital able to book a taxi through its app from the start of next year.
The US ride-hailing firm said it had already recruited a “small number” of taxi drivers and wanted to have several hundred on its books by January.
Representatives of black cab drivers dismissed the idea as a stunt and a way to prop up what they said was an ailing business.
Steve McNamara, general secretary of the Licensed Taxi Drivers' Association (LTDA), said there is "no demand" from passengers for a partnership.
People who book a taxi through the app will still be charged by the meter but will get an estimate of the fare before they start a journey.
Passengers will also pay a £2 booking fee that will be retained by Uber.
Uber said it will not charge new drivers commission for six months.
Andrew Brem, Uber's UK general manager, said: "We're partnering with taxi drivers across the world.
"Black cabs are an iconic part of the capital, loved by Londoners and visitors alike, and we are proud to work side by side.”
Taxi drivers in Paris, New York, Rome and other major cities already use the app, he added.
McNamara replied: "We are not aware of any drivers having been recruited and don't believe our members will even consider joining the app, given its well-documented poor record on everything from passenger safety to workers' rights in London."
A number of apps already exist to book black cabs, McNamara added.