French police and airport authorities said Saturday graffiti, much of it in Arabic, had been found sprayed on four aircraft belonging to British carrier Easyjet (Other OTC: EJTTF - news) and a plane from Spanish airline Vueling at two airports.
Three of the jets had been defaced at Lyon airport in eastern France with two others sprayed at the Paris hub of Roissy-Charles-de-Gaulle, police said.
A police source added authorities believed the graffiti had been painted on prior to the jets' arrival in France, but that the issue posed questions about airport security.
The words "Allah Akbar" were found to have been scrawled on a fuel tank hatch of one Easyjet plane at Charles de Gaulle airport on Tuesday, a day after the aircraft arrived from Budapest, an airport source said, adding it was scrubbed off before the next passengers embarked.
Easyjet serves 17 French destinations and the airline said there had been a "small number" of such cases -- though not all in Arabic -- over the past fortnight since the deadly Paris attacks claimed by Islamist extremists.
?EasyJet assessed this issue, each time working in full consultation with the authorities, and is entirely satisfied it is nothing more than graffiti," the company said in a statement.
The airline stressed that "EasyJet takes very seriously any security related issue and would not operate a flight unless we are entirely satisfied it is completely safe to do so.
"Our security team is experienced at assessing any potential threats and following this assessment this is not considered to be a security issue by both us and the authorities, who share our assessment that it poses no risk whatsoever."
A source close to a French probe into the incidents said the graffiti was "not linked" to the November 13 attacks, noting similar occurrences over recent months involving several other carriers