HSBC, the biggest lender in the city with over 7 million customers in Hong Kong, had its mobile banking service interrupted, with many customers complaining they could not log on to the system on Monday morning.More than 10 HSBC customers contacted the South China Morning Post on Monday morning saying they were unable to log into the mobile banking since 9am.The mobile banking app showed a message saying “access is restricted until we have your valid email address and mobile number,” even though the customers already had their mobile phone numbers and emails in the system.“We are working to resume normal functionality, as some customers may be experiencing difficulties accessing some of our services. We are resolving these as quickly as possible and apologise for any inconvenience caused,” an HSBC spokesman told the SCMP in a statement.This is the second breakdown of the HSBC mobile banking system in six months. In January, the bank’s mobile app and online services were inactive for several hours.Hong Kong resident Erica Wu was unable to log in to her HSBC app, even after trying for 15 minutes from 9.45am. She also tried to top up her PayMe account, HSBC’s peer-to-peer transfer app, but it did not work.