They occurred mainly in the areas of manufacturing, finance, insurance and trading, he said.

'[Cross-border] cases have accounted for a steady 2 per cent of the total reported cases in the past few years, and there is no sign of an upward trend,' Mr Cheung said. He said both sides worked closely during investigations and in arranging to meet witnesses.

'ICAC staff went to the mainland 50 times to interview witnesses for statements last year, while officials of various [prosecutors] on the mainland visited Hong Kong 60 times for the same purpose during the period,' he said.

For instance, Mr Cheung said, a prosecutor in Guangdong helped arrange for a mainland witness to come to Hong Kong.

The witness gave evidence in a case involving the misuse of hundreds of thousands of dollars belonging to a Hong Kong-based arts and crafts products company.

The arrangement was made even though the witness had complained that he had been harassed on the mainland a few days before the suspect was to stand trial in April.

The suspect, a former general manager of the company, was eventually convicted and sentenced to three years in jail.

In another example, a mainland witness came to Hong Kong to testify in a case in which a benefactor of an insurance policy was suspected of bribing the insurance agent to claim damages for a policy holder allegedly struck dead by lightning in Guangdong.

Two insurance agents of MassMutual Asia, Tang Lam-piu and Cheng Hon-chung, were found guilty of deceiving the company in a claim for $700,000.

'With the help of the various [prosecutors] at the county and municipal level, the ICAC was able to take depositions from 13 witnesses belonging to the public security bureau, the verification and certification office, a hospital, a funeral home and the meteorological bureau,' Mr Cheung said. 'From my experience, the mainland does have great determination in fighting bribery and corruption.'