Some years ago when a working group was providing regulations for General Aviation (i.e. that which is not Air Transport nor AW) in the JAA, we produced this text (which is from ICAO Annex 2 - with a little twist):
JAR-OPS 0.485 Performance and compliance with the Rules of the Air
(a) The commander shall satisfy himself that aircraft performance is adequate to enable compliance with the rules of the air, and any restrictions applicable to the airspace in which the flight is being conducted; and shall ensure that an aircraft is:
(1) Except when necessary for take-off or landing at an approved landing site, or except where permitted by the appropriate Authority, not flown over the congested areas of cities, towns or settlements or over an open-air assembly of persons, unless at such a height as will permit, in the event of an emergency arising, a landing to be made without undue hazard to persons or property on the surface.
This may (or may not) have found its way into EASA Ops but I'm not quite sure. It was provided exactly for the case that is being discussed here.
Jim