Officials said many have come from war-torn countries where firearms are “in free circulation”, adding that police are taking “more and more risks” every time they enter the lawless Jungle camp.
They issued the dire warning after a dozen migrants had to be treated for bullet wounds following a mass brawl between 200 Sudanese and African migrants, during which witnesses reported hearing repeated gunshots.
One official said: “Of course there are guns in the Jungle.”
The latest outburst of violence comes after Express.co.uk revealed how 20,000 migrants are massing on the coasts of Normandy ready to attempt the crossing of the Channel by boat.
Details of the mass brawl were reported by French newspaper Nord Littoral, which spoke to sources who witnessed the chaos unfold.
One group confirmed that they “saw a weapon” whilst another said they “heard gunshots” as hundreds of migrants fought in a mass brawl which is believed to have been over money.
Gilles Debove, from the SGP-FO Police union, said: “Yes, it is worrying, One suspects that there are guns in the Jungle.
“The police are very afraid and they are taking more and more risks.”
Multiple sources told the paper that around a dozen migrants were taken to hospitals across the region to be treated for gunshot wounds, all of which were minor.
Mr Debove said some of the wounds may have been caused by air rifles, rather than real weapons.
But Stéphane Duval, director of the Jules Ferry camp where the fight broke out last Thursday, said there were “certainly” guns in the Jungle.
He said whilst he had not directly witnessed a migrant using a firearm, a number of his staff had reported treating residents for gunshot wounds.
Mr Duval said: “Of course there are guns in the Jungle. But I have never seen a Kalashnikov (assault rifle), like you sometimes hear.
“But it is true that we very regularly see knives.”
And Christian Salomé, the director of voluntary migrant help group L’Auberge des Migrants, told the paper that the presence of guns in the Jungle is a reality.
He said: “They [the migrants] come from countries at war, where guns are in free circulation.
“When there is money to win, there are fights.”
The revelations come after sources in northern France told Express.co.uk that the numbers of migrants heading towards Britain has grown significantly in recent weeks.
One official at the Nord prefecture regional government office said: “There are thousands of migrants arriving every day in the cities including Paris, and with the weather improving, we believe there are close to 20,000 migrants in northern France alone.
“The majority hope to get to Britain as quickly as possible.”
Lorry drivers using the lawless port town have warned that it is only a matter of time before one of their number is killed, with many migrants going to increasingly violent lengths to reach the UK.
Truckers have reported migrants using iron bars and knives to attack their cabins and felling trees to block the motorway, so that they can break into the back and hide amongst the cargo in the hope of making it across the Channel.