story identification - Animated movie that had black robots that turned people into stone late 1960s to 1970s

It was a weird sci-fi animated movie I saw only a little bit of it. This is what I recall:

• It was old but had color, so I assume it was late 1960s to early 1970s.



• The animation and style reminded me of Fantastic Planet but it wasn't as psychedelic.


• The setting was an alien planet with all sorts of bizarre creatures.


• The tech was advanced but not a dominant aspect of the planet's culture. The people lived simple and peaceful.


• The protagonist is a man with bluish skin like the others.


• The antagonists were humanoid shaped black robots that shot a beam that would turn people into stone.

Answer

It would seem like the movie your looking for is called Gandahar, though it's not from the time period you stated (it's 1988) it seems to fit all the other criterion.

From IMDb:

Gandahar is a utopian world of rare beauty and tranquility, the result of extensive mutation and genetic experimentation. But the perfect peace is shattered when a mysterious evil force invades this idyllic serenity, turning people into stone with petrifying rays.

Specifically it has black robots who turn blue people to stone with a ray beam. The people also had advanced technology (the genetic experimentation stuff) but lived "peacefully".
Finally, and interestingly enough Fantastic Planet is linked to on IMDb for their similarities in animation style.