Uber asks relevant authorities to investigate claims, and denies it has fallen victim to security breach

It has been reported Uber accounts are being sold for $1 on the 'dark web'

Other users in the U.S. claim they have been charged for trips in London

British customers have reported their accounts being used in U.S. cities

U.S. authorities are looking into how British users of Uber have had taxi trips in the U.S. charged to their account

U.S. authorities have launched an investigation into reports that British and U.S. users of taxi app Uber are being charged for 'phantom' rides they never took.

In recent months, customers in the U.S. claim to have been charged for trips through London, while British users say their accounts are being used in the U.S.

The Guardian reported the agencies have now launched a probe into their claims after Uber asked authorities to investigate.

Among those to claim to have been victim of the scam is Anthea Turner. The TV presenter tweeted to Uber 'account has been hacked nothing to help me on website – this is ridiculous'.

Some users have reportedly had hundreds or even thousands of pounds taken from their accounts.

Last month Uber denied that it had suffered a security breach - but has promised to reimburse all customers who have been charged for journeys that they did not book or take.

Today a spokesmen for Uber told MailOnline the company itself was not being investigated, but it had asked the relevant authorities to look into the issue.

The complaints on Twitter are coming from users across the globe including the States and France.

Record producer Mick Crossley told The Standard he had been hit with a bill for £3,000 for 142 journeys. He said he did not receive notification that the journeys had been booked because someone had changed his contact email address on his account as well.

Some customers have also vented their fury at their inability to get hold of someone at Uber to report the situation to.

The website does not contain a telephone number, only an email function for enquiries.

Anthea Turner was one user who appeared to have struggled to get through to the minicab sharing company.

She tweeted that she couldn't even change her account details because her login details had been changed by someone. Then after appearing to have tried to get a phone number for them, tweeted Uber saying 'your email is saying not valid and the number from 118 500 is not ringing through. Do you exist?'

Last month a spokesperson for Uber categorically denied that there had been a breach at Uber, confirming they were 100 per cent sure that their system had not been compromised.

'We take any issue of this nature very seriously and after investigating have found no evidence of a breach at Uber,' an Uber spokesperson said. 'Attempting to fraudulently access and use Uber accounts is illegal and we notify the authorities about such activity.'

However they admitted that there have been a number of users reporting that their accounts had been used by other people to book journeys.

They said they were still investigating the cause, but that the most likely explanation is that there had been a data breach on another e-commerce website.

Since people often use the same usernames and passwords across several online accounts, fraudsters have attempted to use the data hacked from another site to access Uber accounts.