Taxi app Uber will improve conditions for its British drivers with changes including in-app tipping, after criticism from lawmakers and unions for not giving them more rights.

Drivers for Uber, food courier Deliveroo and other apps tend to work for a number of firms without a fixed contract in what has become known as the "gig economy".

Uber said on Monday it had held meetings and spoken to thousands of them as part of its attempts to improve conditions for its more than 50,000 drivers.

The company promised improvements in July after a government review said those working for such apps, who are mainly self-employed, deserved more rights.

"While drivers have told us they love the freedom of being their own boss, we’ve also clearly heard that we need to make improvements," Uber's UK General Manager Jo Bertram said.

Users will be able to tip drivers via the app rather than just in cash, have to pay 20 pence ($0.26) per minute for making drivers wait after an initial two-minute period and the free cancellation period will be cut from five to two minutes.

Uber said it will make its ratings system fairer and allow drivers to turn down riders they do not wish to take more quickly, which will make it faster for them find a new ride.