CHINESE banks govern credit cards more stringently than their Hong Kong counterparts because they require transactions to be secured with bank deposits, a Mastercard director says. 'The Chinese banks will not approve major transactions if they know that the card holders do not have deposits in the bank accounts,' said Esmond Chan, director of MasterCard International's security and risk department. He said the Chinese credit cards functioned more like debit cards and letters of credit for trade settlement. In Hong Kong, credit cards were not under guarantee. Fears by Chinese banks about controlling credit cards were heightened after the mainland's biggest ever credit fraud (of US$72.3 million) was discovered. It involved the arrest of three employees of the Zhongshan branch of the Bank of China who allegedly siphoned the funds with credit cards and letters of credit. Bank of China, through the issue of 'Great Wall' credit cards, is a member of MasterCard International on the mainland. At the end of last year, the bank had issued more than 1.9 million cards across the country. Mr Chan said the company was aware of the report of the fraud, but he declined to speculate on the cause. 'We are finding out exactly what has happened before we decide on what to do,' he said.