The Licensed Taxi Drivers Association in London has announced it will cause a city-wide gridlock to protest against Uber, a smartphone app that provides taxi-like services.

Uber is a mobile app that connects passengers with drivers of vehicles for hire. You don't have to make a reservation or wait in a taxi line to use Uber. Just compare rates for different verified vehicles and services through Uber, then add a credit card to your account, and set your pick-up location on a map. Uber also lets you check the progress of your car and the route a driver took before paying.

The BBC reported that black-cab drivers in London view Uber as an illegal service simply because it is illegal for private vehicles to have taximeters. Although Uber allows private (but background-checked) drivers to calculate fares, similar to a taximeter, the Transport for London has determined Uber doesn't breach the law. The LTDA wants to fight that decision with a demonstration in June.

"Transport for London not enforcing the Private Hire Vehicles Act is dangerous for Londoners," Steve McNamara, general secretary of the LTDA, told the BBC. "I anticipate that the demonstration against TFL's handling of Uber will attract many many thousands of cabs and cause severe chaos, congestion and confusion across the metropolis."

Uber doesn't have a taximeter installed into a vehicle, but it does make use of data about the time and distance travelled. McNamara argued that this is the same thing, and he expects many thousands of black cab drivers to congest London roads in protest. The LTDA is also seeking a judicial review of Uber - as it is not "fit and proper to hold a London private hire vehicle operator's license."

READ: Uber: The new taxi service hoping to change getting a cab in London

In response to the LTDA's announcement, Jo Bertman, the general manager of Uber in London, said to the BBC: "Competition in my view is always good for the customer because it makes all of us up our game in terms of quality and service. On the driver side, we offer a much more flexible model that is very different from the old-school private hire industry".

Last month, Uber launched in Beijing, making it available in 100 cities around the globe. The San Francisco-based service has introduced many features since starting up four years ago, such as the ability to split cab fare and even order a Christmas tree for home delivery, etc, and these varied and interesting features have likely helped Uber to catch on internationally and spread like wildfire.

"Uber, funded by Google, Goldman Sachs and others, has a stated aim of challenging legislation that is not compatible with its business model," McNamara added. "This is not some philanthropic friendly society, it's an American monster that has no qualms about breaching any and all laws in the pursuit of profit, most of which will never see a penny of tax paid in the UK."