Sunderland University has been hit by “extensive IT disruption” which has “all the hallmarks of a cyber-attack”.
Telephone, website and IT systems are down but face-to-face teaching would continue as far as possible, it said.
The university is working with police and other agencies to find out what has happened.
“We take the security of our systems extremely seriously and will work to resolve the situation as quickly as possible,” a spokesperson said.
Newcastle and Northumbria Universities were targeted by hackers in September last year as the National Cyber Security Centre warned of a spike in attacks on educational institutions.