Hokkaido University has revealed that the personal data of more than 110,000 students and graduates may have been leaked due to unauthorized access of its computer systems by unknown parties.

The university said Wednesday it believed a server at its career placement service center is likely to have been unlawfully accessed.

The server contains personal data, including the names, addresses and birth dates of about 112,600 students and graduates, and information on about 1,600 companies that are used for students' job-hunting activities.

The possible data leak came to light when the server in question sent spam messages to people outside the university on Dec. 27.

The university discovered on Jan. 4 that the server had been communicating with many unspecified external computer servers in and outside the country and cut it off from the network.

Only 12 officials at the career placement service center were authorized to access the internal server, the university said, adding an outsider could have obtained the password to gain unlawful access to the server.

Kazunori Yasuda, vice president of the university, offered an apology to students and companies whose information may have been leaked at a news conference.

"We will ensure proper management (of data) and prevent a recurrence" of a similar incident, he said.

The university set up a panel on Friday to investigate whether the data was actually leaked and whether the university has been managing personal data appropriately.