This seemed to ring a bell but I have not found it.
Timothy Good in Above Top Secret has a chapter on sightings
in France, Italy, Portugal and Spain.
The named cases he gives are these:
1: Marius Dewilde, 10.9.1954, nr. Quarouble, close encounter
with short entities. Paralyzing beam of light. Large steaming
object takes off.
2: Orly Airport 19.2.1956, blips on radar cruises around at
fantastic speeds for four hours. Enormous object seen from
Dakota jet. No landing reported.
3: Valensole Case, 1.7.1965, Maurice Masse finds humanoids
in lavender field.
The same chapter later gives an account of a UFO reported
to have landed at Istrana Military Air Base near Venice, mid-
November, 1973. Murky in details.
Over the page is an account of a UFO which supposedly blacked
out the base at Aviano in 1977. Independent witness outside
base reported it was in total darkness but for one stationary light.
When this "glowing disc" had taken off, the lights came back on.
Denied by military.
Possibly my memory was a conflation of things in this chapter. But
I still think there may have been something reported at Orly nearer
to the story you remember.