Taxi-hailing service Uber is legal in London, Britain's High Court ruled on Friday, following protests from local cab drivers that the app was undercutting their business. Unlike the taxis, which can be flagged down in the street and use a meter to calculate fares, Uber allows customers to book and pay for a taxi using an app on their smartphones. It also provides a second app for drivers to calculate the cost of a journey.

Judge Duncan Ouseley ruled on Friday that the app could not be considered a taximeter and was not therefore illegal.

"A taximeter... is not a device which receives GPS signals in the course of a journey, and forwards GPS data to a server located outside of the vehicle, which calculates a fare ... and sends the fare information back to the device," he said.

Cab drivers in London have been arguing that Uber bypasses local licensing laws. The Licensed Taxi Drivers' Association claimed that the app worked like a meter.

The association said it would appeal.

The court's decision is however separate from a consultation which London's transport authority launched last month, proposing tougher rules which could hit the San Francisco-based app, whose investors include Goldman Sachs and Google.

Uber has been also come under fire in several European countries, including France, Italy and Spain.