The Joint Financial Intelligence Unit (JFIU) - a police and customs anti-money laundering expert group - received 23,282 suspicious transaction reports in 2012, almost double the figure in 2003. 82 percent of the reports last year were made by banks.

Hong Kong authorities convicted 166 people of money laundering in 2012 and 37 people so far this year, according to data from the JFIU, which is responsible for analysing suspicious transactions and is the main channel for banks and other institutions to red-flag suspect transactions.

Two recent court cases in which a young delivery man from Guangdong province and a 61-year-old Hong Kong public housing tenant received jail terms of about 10 years for laundering billions of dollars have hit a nerve in the city, with some saying authorities are only targeting the small fry.

"To some extent, you need to rely on the minor players ... to assist the authorities to identify the major miscreants," Hong Kong director of public prosecutions Kevin Zervos was quoted as saying in local media on Monday.

The public housing tenant was jailed in March for laundering more than HK$6.8 billion ($877 million) through Standard Chartered, Hang Seng Bank, Chiyu Bank, National Commercial Bank, Hua Chiao Commercial Bank, Dao Heng Bank, First Commercial Bank, Hua Nan Bank and Bank of East Asia between 2002 and 2005.

Her conviction came just after the 22-year-old delivery man was jailed for 10 and a half years for laundering HK$13.1 billion ($1.69 billion) in the late 2000s through a corporate account set up with Chiyu Banking Corp, a unit of Bank of China.