Mayor faces calls for probe into Oyster card glitches

Ken Livingstone is today facing demands for an investigation into the Oyster card used by millions of passengers.

The call comes after the plastic smartcard was hit by technical glitches sparked by the New Year fare rises on buses and Tubes.

Liberal Democrats want the £1.2 billion system, which has left thousands of people out of pocket, publicly examined.

Last week the Evening Standard revealed how Transport for London stood to lose thousands of pounds because of a two-month delay in introducingpeak-hour bus fares for Oyster pre-pay users. TfL today admitted to the Standard that Oyster card passengers have been overcharged on the Tube - when they should have been offered discounts.

Another problem was caused when commuters renewed their Oyster cards online on 1 January but were unable to validate them until returning to work three days later - meaning the transaction was cancelled. This meant they had to renew their tickets at the higher 2005 prices.

Lynne Featherstone, Lib-Dem chair of the London Assembly's transport committee, said questions had to be asked about "whether these glitches mask more serious failures".

Oyster card was introduced in 2003 and is now used by 2.2 million passengers. A TfL spokeswoman said most were able to use it without problems.