Two Hong Kong travel agencies have apologised to their customers after confirming separate hacking incidents.
Goldjoy and Big Line Holiday Ltd said their systems were compromised with customer personal data stolen in both incidents.
A police department source said a ransom of 1 bitcoin was demanded from Big by Line the hackers.
"Our company attaches great importance to this incident and deeply apologises to the affected clients," the comoany said in a statement.
"Our network security is now being strengthened. External technical assistance has also been hired to ensure that vulnerabilities in the system are fixed."
Big Line operates city-wide with 13 branches.
Goldjoy, which operates from three locations, said data including ID card numbers, passport details and phone numbers was accessed during the hack.
It is the third such incident in the last three months after major travel agency group WWPKG Holdings revealed its customer database had been illegally accessed.
Authorities have not ruled out a link between all of the cyberattacks.
"Travel agents, as data users, should take all reasonably practicable security measures to protect customers’ personal data.Due to ever-changing technology, causes of cybersecurity incidents have become diversified, making tracing the incidents more challenging," said Hong Kong Privacy Commissioner Stephen Wong Kai-yi.
