Cyberport on Thursday said it is not sure how many people and organisations are affected by a personal data breach.

Some 400 gigabytes of personal data were exposed on the dark web on Tuesday, following a cyber-attack of the company's file storage server in the middle of August.

Cyberport's CEO, Peter Yan, said under no circumstances did the firm consider paying a ransom to the hackers.

He said Cyberport has hired cybersecurity experts to look into what type of information was leaked and who was affected.

Yan said currently, they do not think human error was involved.

"We are trying to understand the whole matter from different aspects," Yan told reporters after the firm held a special board meeting.

"If we find human error, that serious mistakes were made, we will handle them according to established procedures. But right now we don't see any such [mistake]."

Yan said the firm's offering a free service to people who may be affected to track whether their information has been used illegally.

He said Cyberport has tried to notify people who have been confirmed to be affected by the breach, and the company's legal team will study what can be done for individuals who have suffered losses over the incident.

Yan stressed the company has fortified its computer system, and successfully fended off several attacks in recent weeks.

Cyberport said it is forming a task force under its board to follow up on the case, and look into ways to avoid a repeat of what has happened.