Half of the Calais “Jungle” was demolished a few months ago, but the plan by French authorities to slowly rid the ferry port of its lingering migrant problem appears to have spectacularly misfired.

French police say the population migrants gathering here has doubled since June to nearly 10,000, turning the squalid camp into a lawless “no go zone” simmering with inter-ethnic tensions.

On Monday evening, the main street of the camp was buzzing with Afghans, Sudanese and others from war-torn or impoverished nations taking an evening stroll before the nightly attempt to clamber on to a truck on the nearby motorway.

Young English men and women, many of whom local police accuse of encouraging migrants to battle with security forces, mingled with the refugees.

Meanwhile, scores of riot police assembled on the edges of the sprawling camp, ready to quell increasingly frequent outbreaks of inter-ethnic violence.

Last week an Afghan man was killed and several others injured as a couple of hundred Sudanese and Afghans battled each other.

“It’s an explosive situation. There are fights all the time in the camp,” said Gilles Debove, an official with the SGP FO police union, told the Telegraph.

He added that for a long time it was the Afghans who were here in greater numbers, but now it is the Sudanese who have the upper hand.

The streets of the camp, lined with makeshift shops and restaurants, several mosques and a church, were calm on Monday evening.

Rais, a 23-year-old migrant from Jalalabad in Afganistan, was on his way to get a hot meal provided by the Salam charity group at its centre next to a mosque housed in a large white tent.

He has been in the Jungle for two months and says it has got a lot more crowded since he arrived.

“There are fights all the time now. You can get stabbed here for your money,” he said.

Like many here, he is determined to get to Britain.

“England good – make money there,” he said in his rudimentary English.

But he has no money to pay the Afghan, Kurdish and Pakistani people smugglers who frequent the Jungle.

For €8,000 they will get you there in a day, for €3,000 it might take anything from a week to a couple of months, he said.

So Rais is planning to sneak onto a lorry.

But with the extra security measures in place around the ferry port and the Channel tunnel entrance, that is a risky and every more difficult venture.

For the moment Rais is lying low, spending his days hanging about the camp and his nights sleeping in a tent with about 20 other Afghans.

About 1,500 live in containers provided by local authorities, and some other live in DIY huts.

But police have now barred building material coming into the camp, and tents, which will provide little protection against the approaching winter cold, are now the only option for the newcomers.

There are some 751 children living in the camp, 608 if them unaccompanied.