Hong Kong - Banking giant HSBC was on Thursday under fire after admitting it had lost the data of 159,000 accounts from a Hong Kong branch.

The data was held on a internet server which is understood to have gone missing from the Kwun Tong branch of the bank while it was undergoing renovation last month.

The loss was reported to the police and the Hong Kong Monetary Authority on April 26, but many customers affected only learnt of the security breach after reading reports in the local media.

In a statement issued Wednesday, the bank acknowledged a server had disappeared containing the account numbers, names and transaction details of 159,000 accounts.

However, it said the server did not contain customers PIN numbers or user IDs and insisted that the likelihood of anyone gaining access to the data was low, as the server was protected by multiple security systems.

Angry customers turning up at the branch to demand an explanation were told to wait one or two days, to check their accounts regularly and be on their guard against people claiming to be bank employees.

However, chairman of the Legislative Council's security panel James To said the security breach was "absurd" and warned that the types of data lost wound be enough for fraudsters to try and obtain more important information.

"I would not be surprised if someone handed over his or her PIN numbers after receiving detailed transaction records purportedly to be from the bank," said To.

To said the bank should have gone public with the loss much earlier to alert customers. He called on the Hong Kong Monetary Authority (HKMA) to demand a report from HSBC on the remedial measures it had taken and planned to take.

The HKMA said it had asked the HSBC to contact the affected customers explaining the implications and giving them advice on what steps to take to protect their accounts. (dpa)