The probe comes two weeks after 130 people were killed by twisted Islamic State terrorists in co-ordinated attacks across Paris.
Airports in the capital have tightened security since the horrific shootings and bombings amid fears of follow-up attacks.
Airline security expert Philip Baum said: "Graffiti in itself won't hurt anybody.
"But the ability of anyone to place a prohibited item near fuel tanks is a concern, of course."
He added: "We know there are people working in restricted areas of airports with extremist sympathies."
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