Authorities said on Friday that 7,249 email addresses registered with Hongkong Post have been leaked, after an unauthorised party made countless attempts to try and guess the email addresses of its account holders.

However, the department said the unauthorised party had not been able to get hold of the account holders' personal information such as login name and password, or details of their account transactions.

The department added that it has informed affected account holders of the incident, which happened on Wednesday.

It said it has reported the case to the police and the Office of the Privacy Commissioner for Personal Data, and is seeking advice from the Office of the Government Chief Information Officer on how to beef up security.

"Hongkong Post wishes to alert members of the public to refrain from clicking on any embedded links or providing any personal or financial information such as credit card information, or making any payment to suspicious emails or SMS messages alleged to be sent by Hongkong Post," it said in a statement.

Officials said members of the public may call the Hongkong Post General Enquiry Hotline at 2921-2222 if they have any concerns.