Powder Keg Paris: 300,000 illegal migrants are living in one French suburb. Many rely on crime or the 'black economy' to get by and live in poverty. Rule of French law, equality, religious freedom, was lost in the suburb. There are more mosques there than anywhere else and There are around 350 known jihadists living in Saint-Denis, while 1,700 are believed to have returned to France after fighting for IS in Syria, with 15,000 terrorism suspects in France. On a steamy summer's night, the sounds and smells are of Africa. Hawkers grill meat on fires built inside shopping trolleys. People jostle and sweat; thick smoke hangs in the air. West African women — les Reines de Marchand, the Queens of the Market — sell fake designer clothes. Hustlers in sunglasses work the crowds.

Some voices are from sub-Saharan Africa — Ivory Coast, Nigeria, Sudan, Eritrea, Congo, Guinea, Sierra Leone. Afghans shout and joke in Pashtun. There are thousands at this open market — haggling, eating and drinking.

At the World Express cafe, groups of men argue in Arabic. On side streets, men smoke shisha pipes and talk on every corner. Women shop in veils and scarves, always accompanied by a male relative.

As a white European, I attract odd looks. When I take out my mobile phone for a photograph, a young man jumps in front of me, waving his index finger in my face, shouting: 'La! La! La!' (No! No! No!)

Yet this is not an exotic, far-flung destination. This is France. Moreover, this is Paris and only six miles from the Eiffel Tower.

The reason for all this activity — in an area which even the most optimistic estate agent would struggle to sell as 'cosmopolitan and bohemian' — is quite simple: immigration on a mammoth scale.

This area is called Saint-Denis in the north-east of the city, where the Basilica holds the resting places of many French kings and queens.

Recently, it was reported that this sprawling district now holds as many as 300,000 illegal immigrants, many of whom rely on crime or the 'black economy' to make money. The official legal population in Saint-Denis is estimated at 1.5 million.

Not only that, according to French parliamentarians in a new report that's causing much anguish across the nation, as many as 420,000 legal residents here are living 'below the official poverty line'.

The scale of the problem grows each day. An estimated 80 migrants arrive in Paris every 24 hours — 550 a week.

There are an estimated 135 different nationalities in Saint-Denis, most extremely poor, including an estimated 600,000 Muslims from North African or sub-Saharan African backgrounds.

Having spent several days in Saint-Denis, it's clear to me that the area is already lost to France — to the rule of French law, equality, religious freedom, and even access to the streets by the police themselves.

Indeed, this is a parallel state — a state within a state, with its own rules and religious courts — where allegiance to Islam comes ahead of fealty to France.