A technical glitch disrupted internet banking and ATM withdrawals for customers of HSBC and its sister bank, Hang Seng, for about two hours on Sunday.
"We're sorry, this service is temporarily unavailable. Please try again later," a message on HSBC's mobile app showed, while some ATM machines were also down.
Services gradually resumed to normal after noon.
According to the websites of HSBC and Hang Seng Bank, system upgrades or maintenance took place in the early hours of Sunday.
Francis Fong, honorary president of Hong Kong Information Technology Federation, said he believes the incident was caused by the failure to resume normal banking operations after system maintenance.
He said the impact wasn't huge as services were back online after around two hours and the glitch happened on the weekend.
Still, Fong called on the bank to take steps to prevent similar mishaps from happening again.
"I think all of this system maintenance, originally, should be uninterrupted. But there are unforeseeable events happening, and I hope HSBC will learn from this experience and try to minimise the problem that appeared this time and to prevent further interruption again in the future."
Finance sector legislator Chan Chun-ying said he expects the Monetary Authority to demand the two banks to submit a detailed report on the incident.
Last updated: 2022-06-05 HKT 17:30