Serb air traffic control say that the Air France jet didn't follow instructions and had descended below the approved altitude, almost causing and accident with the El Al jet. In any case, this should be investigated. Shouldn't be hard, all the tapes and telemetry are available.
Palestinians report IDF airstrikes on Islamic Jihad targets in southern Gaza Strip (Haaretz)
from the article: El Al, Air France planes nearly collide over Serbia