Uber was stripped of its London operating licence on Mondayfor the second time in just over two years after the city's regulator said a"pattern of failures" on safety and security meant the taxi app wasnot fit and proper.

A change to Uber's systems allowed unauthorised drivers toupload their photos to other driver accounts, meaning they could pick uppassengers as if they were the booked driver, which happened in at least 14,000trips, Transport for London (TfL) said.

The Silicon Valley-based company, which has faced pushbackfrom authorities and existing operators in several countries, has 21 days toappeal and can continue to take rides during the process, which is likely toinclude court action and could drag on for months.

"TfL has identified a pattern of failures by thecompany including several breaches that placed passengers and their safety atrisk," the regulator said on Monday, the day the firm's licence expires.

"Despite addressing some of these issues, TfL does nothave confidence that similar issues will not reoccur in the future, which hasled it to conclude that the company is not fit and proper at this time."Uber, which has roughly 45,000 drivers in London, did not offer an immediatecomment.

Uber and TfL have been engaged in a long-running battlesince TfL rejected a renewal request in 2017, citing shortcomings in the firm'sapproach to reporting serious criminal offences and driver background checks. Ajudge in 2018 then granted Uber a probationary 15-month licence, after thecompany made several changes to its business model.

In September, TfL gave Uber just a two-month extension, far short of the maximum possible five years, and imposed further conditions covering ride-sharing, appropriate insurance and driver document checks.

Ahead of the latest decision, Uber said it would introduce measures such as a discrimination button enabling drivers and riders to report abuse, enhanced safety training for drivers and a direct connection to the emergency services.