Uber has been accused by police in England of allowing a driver who sexually assaulted a passenger to strike again by not reporting the attack, along with other serious crimes.
In a strongly worded letter, Inspector Neil Billany of the Metropolitan Police's taxi and private hire team suggested the company was putting concerns for its reputation over public safety.
He cited the case of a man who worked for Uber being allowed to stay on the books despite an allegation of sexual assault, leading to another, "more serious" attack on a woman in his car.
"Had Uber notified police after the first offence it would be right to assume that the second would have been prevented," the inspector wrote in his letter to Helen Chapman, head of taxis and private hire at Transport for London (TfL).
The private hire firm allows passengers to book taxis through their smartphones and operates in cities across the UK.
Among a string of serious crimes it allegedly failed to report included more sexual assaults and an incident in which a driver produced what was thought to be pepper spray during a road-rage argument.
Mr Billany speculated that Uber was deciding which matters to pass on to police based on what was "less damaging to reputation over serious offences".
He said Uber's policy of logging the criminal complaints with TfL instead had prompted delays of up to seven months before they were investigated by officers.
TfL said delays in reporting crimes to the police were "totally unacceptable", adding: "We have been in contact with the operator to ask them to respond to these concerns."
Uber's long-term licence comes up for renewal by TfL at the end of September.
The inspector's correspondence, dated April 12, was obtained under Freedom of Information laws by the deputy chairwoman of the transport committee at London City Hall, Caroline Pidgeon.
In 2016, the Met Police were made aware of six sexual assaults, two public order offences and one assault reported by Uber to TfL, Mr Billany said.
He wrote: "The two public order offences mentioned above are subject to a 6 month prosecution time limit so subsequently both were taken no further as by the time we became aware of the offence we had no power to proceed, despite both having clear evidence of an offence taking place.
"By not reporting to police promptly they are allowing situations to develop that clearly affect the safety and security of the public."
When approached by police, Uber refused to provide any information unless it was formally requested under Data Protection laws, Mr Billany claimed.
Uber told The Sunday Times the refusal to help was due to a misunderstanding and said the pepper spray mentioned in the letter had actually been a spray to identify criminals, which was legal.
It said: "We were surprised by this letter as in no way does it reflect the good working relationship we have with the police.
"We advise people to report serious incidents to the police and support any subsequent investigations, but respect the rights of individuals to decide whether or not to make such reports."