Tube travellers have had their online payment accounts hacked, according to Transport for London (TfL).
Some 1,200 customers attempting to access their online Oyster card accounts have reported being denied access since Wednesday.
TfL said while no customer payment details had been breached it had “temporarily suspended” online contactless and Oyster accounts.
The transport body has six million online Oyster account holders.
A spokeswoman said the numbers compromised is believed to be small and an initial investigation indicated the Oyster online service had not been compromised.
“As a precautionary measure and to protect our customers’ data ... Read even more