Hi!
I think it's a Russian MAT engine. 10cc engine (.61). Some of my CL-flying friends competing in F2D combat bought some of these (10cc , 6,5cc and 3,5cc engines) 10years ago or so when they competed in Russia.
I think this engine is a Pre-MDS engine made by the same people that makes MDS engines today.
Performance and quality is not so good though.

Regards!
Jan Karlsson
Sweden