Nearly 28,000 safety-related complaints were made about Uber drivers in London in a six-month period, it has emerged.
The safety concerns were among almost 600,000 complaints made to the firm between December 2018 and May 2019.
The figures were included in a newly released letter from Transport for London (TfL) which sets out its reasons for not granting Uber a private hire vehicle operator licence.
Uber said safety was its "priority" and is appealing TfL's decision.
TfL acknowledged, however, that 27,799 safety-related complaints, was a "statistically small" amount compared to the total number of trips made by Uber drivers in the capital, but it said "the risks to the public arising out of unsafe driver conduct are significant".
TfL announced in November last year that it considered Uber "not fit and proper" to hold a operator's licence.
The letter sets out further details about some of the issues found with the company.
Other concerns included 12 drivers who were found to be working for Uber during 2018 with incorrect insurance.
Uber and two of the offenders, who between them had made more than 1,400 trips, were convicted in July 2019 as a result and ordered to pay fines.
It is the second time the company has been convicted for insurance breaches, the first being in 2014.
TfL commented in its letter that Uber "should have learned the lessons from the previous conviction".
More than 20 drivers were also found to have bypassed Uber's security systems, managing to upload their image to another driver's account so they could make the trips instead.
At least five of the cases involved drivers who had previously been dismissed by Uber, while another was a person who had previously lost their TfL licence after accepting a caution for downloading and distributing an indecent image of a child.
Uber are still able to operate while they appeal and TfL said it would "be for a magistrate to determine if they are fit and proper".
Jamie Heywood, Uber's regional general manager for Northern and Eastern Europe, said the company was "committed to Londoners and are working closely with TfL to address their concerns and requests".
A spokeswoman for the firm said they would also "soon be introducing a new facial matching process" to combat photo fraud.
Source: BBC