Apparently he used to threaten students to stop making left wing films:

LWLies: I wanted to ask you briefly about Ingmar Bergman. Were you affected by his death?

Andersson: Of course in my opinion he’s – it’s hard to say – but in my opinion he’s a little overrated. He made in the beginning of the ’60s I think there were four movies that are excellent, brilliant, good art and cinematography, but there are so many bad movies he made. And he was also very right wing politically. He was almost a fascist, he was a Nazi sympathiser, and when he grew up he was very coloured by fascistic values. He never left that himself, and it also coloured his person. He was not a nice person. He was a so-called inspector of the film school that I attended, and each term we were called and we had to go to his office and he gave some advice, or even some threats, and he said, ‘If you don’t stop making left wing movie…’ because a lot of the students were left wing at the time, Vietnam and so on… “if you continue with that you will never have the possibility to make features. I will influence the board to stop you.”

https://web.archive.org/web/20090803010358/http://www.littlewhitelies.co.uk/interviews/roy-andersson/