Less than 10% of Customs cases require covert surveillance, and the cases that do usually involve serious crimes, Commissioner of Customs & Excise Timothy Tong says.

He told reporters today the Interception of Communications & Surveillance Bill, endorsed by lawmakers yesterday, plays a key role in disciplinary services' investigations and enforcement. Noting the bill will give enforcement agencies necessary power, Mr Tong stressed it has already taken into account the public's privacy and interests.

ICAC Commissioner Raymond Wong said the bill has struck a balance between protecting the public's privacy and effective law enforcement. The bill has laid down situations when law -enforcement agencies can conduct covert surveillance. It also requires the disciplinary services to notify the courts and clearly outline the reasons for such action, he added.

Mr Wong said internal guidelines will be devised and training for staff will be arranged to help familiarise them with the law requirements.