Taxi app Uber is to launch a car-sharing service in London which it claims will help cut congestion.

UberPOOL will allow up to three passengers to share a car and save money on the standard fare.

The scheme was first launched in San Francisco in September last year and now makes up over half of all Uber trips in the US city.

London will become only the second European city - after Paris - to have UberPOOL when it begins operation at 4pm on Friday.

Passengers will save 25% compared to the standard uberX fare. Each pick-up is restricted to a maximum of two people, with no more than three passengers in a car at any one time.

The introduction of the scheme comes while Transport for London (TfL) is holding a consultation on a series of measures that would affect Uber.

The proposals - which TfL say could "improve and inform" the regulations that govern the capital's private-hire trade - include enforcing an interval of at least five minutes between a booking and the start of a journey to allow drivers to plan an appropriate route.

London mayor Boris Johnson has blamed Uber for increasing traffic levels in the city.

The number of private-hire driver licences in London has risen from 65,000 in March 2013 to 92,000 earlier this month, according to TfL figures.

Uber's UK general manager Jo Bertram claimed uberPOOL will reduce congestion on the capital's roads.

She said: "UberPOOL makes it easy and affordable for people going in the same direction at the same time to share the trip.

"That means cheaper rides for passengers, less time between trips for drivers and fewer cars on the city's streets over time.

"By getting more bums on previously empty seats, this new service will help cut congestion and pollution in London."

The service will initially only be available for journeys starting in central London or Heathrow Airport.

Uber currently operates in more than a dozen UK cities.