A few weeks ago we saw similar, but over the Balkans area. Numerous aircraft reporting the same thing to ATC, from northern Greece up to Croatia. On approach to SKG we had an extremely bright unusual fixed light in the sky (at night). Northbound we saw 3 lights moving as described, aircraft closer to it said they could see the objects above them moving in a manner aircraft aren't known to move, estimated at FL500. No idea what they were.