Hong Kong’s banking regulator has fined four banks, including local units of Industrial and Commercial Bank of China (601398.SS) and UBS (UBSG.S), a combined HK$44.2 million ($5.67 million) for breaches of anti-money laundering rules.

The four banks had failed to carry out appropriate customer due diligence, the Hong Kong Monetary Authority said in a statement.

ICBC (Asia) was fined HK$20.7 million. UBS HK was fined HK$9 million. China Construction Bank (Asia) was fined HK$8.5 million. CTBC Bank Hong Kong was fined $6 million.

“Banks should make reference to these case examples to review data quality and respective transaction monitoring system effectiveness,” said Carmen Chu, the HKMA’s executive director (Enforcement and AML).

“The identified deficiencies in the four cases occurred in a period … when industry understanding and experience were less mature, and since then, significant progress has been made by the industry, including the banks concerned.”

UBS declined to comment, ICBC Asia, CCB Asia and CTBC could not be immediately reached for comment outside normal business hours.