Omega, or Ofmega, which is an amalgamation of the old Ambrosio, Magistroni, etc.?

I presume it has an Italian-threaded BB, and given your location, it probably is Italian.

The thick seat tube walls indicate plain gauge carbon steel, for an entry-level frame of about Peugeot AO-8/UO-8/UE-8 quality. Since it's Italian and looks to have a well-designed frame geometry, I'll bet it rides and handles better than most bikes in its class. (We sold a few bottom-of-the-line Atala bikes when I worked at a Peugeot/Nishiki dealership in the early 1970s, and the Atalas were a pleasure to ride, compared to the same-priced Nishiki and Peugeot models.)