The online taxi app Uber won't be granted a new licence to operate in London as a result of its failings, according to Transport for London.
The regulator said the firm was not "fit and proper" as a licence holder, despite making a number of positive changes to its operations.
Uber lost its licence originally two years ago but was granted two extensions, the last of which expired yesterday (Sunday).
The firm will appeal and can continue to operate as the appeal process is ongoing.
Uber has around 45,000 drivers working for it in London which is one of its top markets globally.
But Transport for London said it had found a "pattern of failures" which placed passenger safety and security at risk.
The failures include a change to Uber's systems allowing unauthorised drivers to upload their photographs to other drivers' accounts.
It means around 14,000 fraudulent trips were carried out in London in late 2018 and early 2019, according to TfL.
Read more of today's top stories
London Mayor Sadiq Khan said: "I know this decision may be unpopular with Uber users, but their safety is the paramount concern.
"Regulations are there to keep Londoners safe."
Uber also operates in cities across the UK including Manchester and Liverpool, Leeds, Stoke, York, Sheffield, Newcastle, Nottingham, Birmingham and Bristol.
The company described the decision as "wrong" and "extraordinary" and said it had made fundamental changes to its business since 2017.
