China is the key suspect in the theft of huge volumes of highly sensitive personal data from the Australian National University, which intelligence officials now fear could be used to "groom" students as informants before they move into the Australian public service.

The hacking, which occurred despite the government's elite electronic spy agency last year helping the university bolster its cyber defences, hoovered up 19 years' worth of personal data including bank numbers, tax details and academic records of students and staff.

Authorities have described the ANU attack - the second on the university in a year - as "sophisticated". Credit:Elesa Kurtz

Senior intelligence figures have been alarmed by the scale of the breach and the possible motivations behind it, with widespread ramifications for other Australian universities.

The Sydney Morning Herald and The Age can reveal the intelligence community fears the data will be used to target promising young students in the hope they can be used as informants as they move through their careers, notably in government departments and even intelligence agencies.