Police have accused Uber of not reporting sex attacks committed by drivers, with 48 alleged to have taken place.
The company also faces accusations it failed to report other 'serious crimes' and obstructed police investigations.
It is facing a licence review in London, one the 20 British cities in which it operates and its biggest European market.
Uber has been accused of failing to report 48 sexual assaults and other crime committed by drivers, including a firearms offence
Head of the Metropolitan police's taxi and private hire unit Neil Billany said Uber, which has a presence in 633 cities worldwide, seemed to be 'deciding what [crimes] to support' in a letter seen by The Sunday Times.
He spoke of a 'significant concern' that Uber was only reporting 'less serious matters' that would be 'less damaging to [its] reputation'.
He accused Uber of 'allowing situations to develop that clearly affect the safety and security of the public' by keeping drivers' crimes from police — including at least six sexual assaults on passengers.
In at least one of the sex cases, Uber continued to employ the driver, who then carried out a more serious sexual assault on a second woman passenger.
Mr Billany said two public order offences and an assault also went unreported.
'Had Uber notified police after the first offence, it would be right to assume the second would have been prevented.
'The victims complained to Uber and were left "strongly under the impression" it would tell police, but it did not do so.'
Neil Billany's letter, which was obtained by an FOI from Caroline Pidgeon, says Uber is covering up sex attacks
In the year to February 2017, Scotland Yard recorded 48 alleged sexual assaults by Uber drivers, most of which were