The University of Maastricht paid ‘several hundred thousand euros’ to hackers who broke into the computer system shortly before the Christmas break, according to university news website Observant.

After making the payment the hackers gave university cyber experts the key to get back access to the system, sources told the magazine. The university itself has not commented on the claims.

The university was hit on December 24 and the hack resulted in the email and Windows systems being frozen.

Cyber crime experts have suggested that the hack was the work of a Russian group known as TA505, who focus on ransom-ware but others have dismissed this as speculation.

Although the system is not completely up and running again, classes will resume on January 6 after the winter break and resits will take place as planned, the university authorities say.