Eastern-European? children’s? musical? film with a boy who has talking-animal friends that are 2-D/cutout puppets, escapes from hospital or asylum

Saw parts of this on (Russian) TV around 2002, was not in English, nor Russian I think, maybe a Polish or Czech movie that seemed like a children’s movie but was very surreal. Color, I’d guess it dates to the mid 60s or early 70s. The main character was a small boy and he went around with talking-animal characters who were like puppets, but had no depth (2-D) as if they were cut out of cardboard, yet they had moving mouths and eyelids.

The scene I saw appeared to be taking place in a hospital or asylum and the boy was trying to sneak out (or in?), and at one point was being chased by figures in white sheets (ghosts?). There was also singing, so maybe it was a musical?

Made a big impression due to its weirdness but due to the language barrier and circumstance I was never able to figure out what movie this could have been…

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