More than 400 counterfeit $500 notes were found in the bank's machines Police have arrested 11 people, including a 15-year-old boy, over the discovery of hundreds of counterfeit $500 notes in HSBC deposit machines. Detectives from the Commercial Crime Bureau started their operation on Saturday after receiving a report from HSBC the previous day that it had discovered counterfeits in four of its 169 deposit machines. At least 400 fakes were discovered. It is believed the counterfeits were part of a scam in which genuine notes were withdrawn after the fakes were deposited at four HSBC Instant Deposit Machines in Yuen Long, Mongkok and Causeway Bay. Sources said the counterfeits of old-design $500 notes were of poor quality. Police are investigating how they escaped detection by the machines. The discovery of the fakes worth $200,000-plus far exceeds the haul of 162 counterfeit $500 notes detected in all of last year. Nine men and two women aged 15 to 25 were arrested for passing counterfeit notes. Three were released on bail, while the others, including the 15-year-old, remained in detention. It is understood that the suspects were tracked down after police examined the details of the accounts in which the counterfeits were deposited. The fake notes were discovered during an investigation into an apparently unrelated technical glitch, in which deposits were not immediately credited to customers' accounts. A police spokesman declined to reveal more details of the case, saying the operation was continuing. HSBC yesterday resumed the operation of 150 of the 169 deposit-only machines that were closed on Friday and over the weekend. The remaining 19 deposit machines - located at self-service outlets where there are no bank staff on duty - would remain shut until further notice. A further 93 deposit machines for Hang Seng Bank, which uses the same machine model as HSBC, have been shut since Friday. Hang Seng resumed the operation of 36 of the machines yesterday. Both Hang Seng and HSBC said their machines would only operate during bank opening hours. Customers who wanted to make deposits after bank hours would have to do so via automatic teller machines with deposit functions. Unlike a deposit machine, making a deposit through an ATM requires the customer to put the money in an envelope with a slip containing the account details. The money is not credited into the account until bank staff check the cash. A spokeswoman from HSBC said it was the first time that their deposit machines were known to have accepted fake notes. A spokeswoman for Hang Seng Bank said they were looking at ways to improve the deposit machines.