Taxi drivers in cities across Europe brought traffic to a standstill on Wednesday in a go-slow protest against a mobile phone app which they say is damaging their livelihood.

In Barcelona, travellers were left stranded at stations and airports with no taxis to jump in.

In Paris, drivers blocked the Charles de Gaulle and Orly airports and prevented private-car services from picking up passengers.

While in London, black-cab drivers descended on Trafalgar Square, chanting their anger at the mayor of London, Boris Johnson.

The mobile phone app being targetted is Uber, although there are other similar applications.

Passengers can use Uber to track a local car, then book and pay for private journeys online. The drivers don’t need to be trained or licensed or take out the same insurance, enabling them to undercut traditional taxi drivers.

The chairman of the Berlin taxi union, Richard Leipold, warned that passenger safety could not be guaranteed when using Uber or similar apps.

“Certainly the moment you use one of these apps there is a danger, not only for the taxi trade, there’s nothing we can do about this, but there is a danger for anyone who uses it because they are not insured. You cannot be sure that a safe and qualified driver drives the car and has car insurance,” Leipold said.

The Californina-based company which is backed by Goldman Sachs and Google says the taxi industry hasn’t faced competition for decades and that Uber was “bringing choice to customers.”

Taxi drivers say they don’t object to competition but want regulators to apply the same tough rules to Uber drivers.