Hong Kong's Privacy Commissioner for Personal Data Roderick Woo on Friday urged the issuer of Octopus card, the city's most widely used smart card, to better protect customers' personal information.

Briefing the media on his interim investigation report on Octopus Rewards Limited, Woo said the company should not collect and disclose excessive personal data. It should state clearly where the collection of particular items of information is optional.

On the use of privacy data, he suggested the print characters in any contract be of a font size reasonably readable by customers without optical aids. The scope to whom the personal data can be transferred should also be reasonably specific.

"The applicant should be given an informed choice to authorize their personal data to be used for direct marketing purposes. Consent should be expressed and not be deemed given," Woo said.

He also recommended that the company should assess the adequacy of privacy protection its business partner offers before entering into any arrangement on personal data transfer, have a professional third party to verify erasure of personal data the business partner holds, and particularly specify in the agreement with the business partner that data transfer to any place outside Hong Kong is strictly prohibited.

Octopus Card, Hong Kong's mass transit refill cards, is widely used in the city to pay public transportation fares, as well as retailers who accept Octopus, such as convenience stores or restaurants.

Octopus Holdings admitted this week that the Octopus Rewards scheme, launched 4 years ago and operated by two subsidiaries Octopus Rewards and Octopus Connect, sold the data of 1.97 million customers to its six partners in the scheme.

95 percent of people in Hong Kong aged 16 to 65 use Octopus to travel, shop and dine, and over 2.4 million customers have registered for the widely adopted Octopus Rewards program, Octopus Holdings claimed on its website.

Octopus Cards is wholly owned by Octopus Holdings, whose shareholders are the major transport operators in Hong Kong, with the Mass Transit Railway Corporation the biggest at 57.4 percent.