The airplane had just taken off from Paris Orly airport on Sunday morning bound for Cayenne in French Guiana when it experienced some technical problems, according to reports.

In order to be able to land safely it was forced to dump “dozens of tonnes of fuel”.

Sources told AFP that the jet was forced to jettison its fuel over the Ile de France region before landing at Charles de Gaulle airport to the north of the city.

According to Le Parisien newspaper the huge fuel dump took place over the famous Forest of Fontainebleau, an area popular with hikers and climbers, especially on Sundays.

Le Parisien spoke to a witness in the aviation sector who said: “The aircraft was flying at a height of less than 6,000 metres and dropped dozens of tonnes of kerosene over the forest.”

And the site Flightradar24.com which follows real time positions of aircraft showed that the plane made several turns over the forest.

That was enough to draw an angry response from the mayor of the town.

“It’s outrageous that this procedure is still allowed,” Frederick Valletoux said on Twitter.

“The forest of Fontainebleau has ten million visitors a year and is the most protected natural space in France,” he added.

The forest is spread over some 25,000 hectares to the south west of Paris and contains some 300km of marked footpaths for hikers.

The good news for anyone in Fontainebleau forest on Sunday is that much of the fuel is likely to have vaporized before hitting the ground. But the jettison does have an impact on the environment.

But according to the airline Boeing: “Even though dumped fuel is vaporized, it is still suspended in the atmosphere. The odour can be pronounced and the fuel will eventually reach the ground.”

(Philipp Hertzog)

(Jerome Bon)

Air France confirmed the fuel dump took place, but did not specify the location.

“Flight AF852 Paris-Orly to Cayenne turned around following engine failure at take-off,” a spokesperson for Air France said, adding that a fuel dump took place “according to procedures”.

The type of fuel dump is “an exceptional measure that is taken at the discretion of the crew, but which requires authorisation from air traffic control. The aim is to lighten the aircraft,” said the spokesperson.

In tweet AIr France said the zone for the fuel dump was imposed by aviation authorities, not the company itself.

Certain aircraft have a maximum landing weight lower than their maximum take off weight.

At the start of long haul trips requiring lots of fuel the maximum landing weight is often exceeded so if a plane is forced to land earlier than expected then it requires a fuel dump.