The pile of money left on unused Oyster cards has reached a quarter of a billon pounds, official figures show.
It has led to fresh calls for Transport for London to scrap the rule that someone buying an Oyster, paying the £5 deposit and loading it with cash can only claim a refund after 48 hours.
There was hope today that the restriction could now be eased so passengers can obtain refunds more quickly.
The amount of cash on dormant Oysters — those left unused for 12 months or more — is increasing by more than £1 million a month and now stands at a record-breaking £250.87 million. The number of such cards has risen by two million to 45.55 million in six months.
Caroline Pidgeon, chairwoman of the London Assembly transport committee, said: “It is staggering that TfL has now accumulated a huge cash pile of over a quarter of a billion pounds.
“Since I first raised this issue five years ago the amount has increased fivefold and shows every sign of continuing to even dizzier heights. TfL must make it easier to reclaim money, starting with ending the 48-hour restriction on refunds. TfL must step up the information provided to the public over how they can reclaim their money back.”
A report by London TravelWatch ex-amining the impact of Tube ticket office closures recommended changes including removing the 48-hour restriction, saying it “does not represent good customer practice, especially for visitors who are only here for a short time”.
The watchdog said: “We understand TfL are looking into [ending the 48-hour rule], as before this can be done they will need to make technical adjustments and ensure there is protection against credit/debit card fraud.”
A TfL spokesman said it was examining reducing the 48-hour restriction and the delay was due to “our wider fraud prevention measures”.
Shashi Verma, TfL’s chief technology officer, added: “We’re committed to ensuring customers can get back credit on their cards. We regularly publish how people can obtain a refund … from any ticket machine, our visitor information centres or on 0343 222 1234.”