The bricks up front are normal trans-clear bricks to compare.
The plastic seems to have a match with PRIMA bricks. They sound and feel the same.
These bricks showed up on Ebay in Denmark together with Byg Selv / X-clone bricks. It is not weird to see why as they look very similar.
Picture to compare:
Visibly it is more similar to Byg Selv / X-clone, but plastic material and the sound they make is more similar to PRIMA.
The mold is the “short bar G” / “blockletter with number” mold.
However on most of the bricks is no mold number visible. Most likely because of the plastic type and wear.
Multiple of the bricks are slightly marbled with what looks like white or possibly another type of trans-clear.
[Original posts and comments on Flickr: bricks, comparison.]