Drivers of London's traditional black cabs have blocked some of the city's busiest streets in a protest at the lack of regulations imposed on Uber.

Thousands of drivers brought their vehicles to a standstill around Parliament Square and Whitehall, near the Houses of Parliament, tooting their horns at regular intervals to make their discontent clear.

They say that, while they have to comply with a string of regulations — including passing The Knowledge, a famously tough test in which they have to memorise tens of thousands of destinations — drivers for the ride-calling app do not.

"We are not saying do away with Uber, we just want them to have the same regulations that we have," said Steve Wilson, 47, who has driven a black cab for 22 years.

Uber insists it does not want to put black cabs out of business.

"Common sense regulations combined with new technology can help ensure that black cabs and apps like Uber live side by side," it said in a statement.

"It's the best of both worlds. Londoners and tourists would be free to choose whether they want to hail a car on the street or push a button and get a ride for generations to come."

Reportedly valued at over $60 billion ($85 billion AUD), Uber has expanded rapidly in cities around the world but has faced a string of regulatory challenges and opposition from longer-serving cab drivers.

AFP