Oliver Conway

I'm heading now to meet a local lawyer, somebody who's been active for years supporting the victims of gangland killings.

But in the last week or so, she's become so afraid for her own safety that she's taken a step back.

And she's going to talk to us now, but only if we hide her name.

We're seeing increasingly youngsters, teenagers involved in the gangs now.

In a big convoy, French police drive towards the outskirts of Marseille to an area where the drug gangs are dominant.

The aim is to disrupt their trade.

OK, we're just running with the French police here around an apartment block.

They're trying to seal off to make sure that there are no drug dealers here.

We're in a stairwell now.

There are maybe six, seven policemen.

They've surrounded one young man.

They've got him up against the wall.

They're searching him.

We understand he's 18 years old.

The youngster then begs the police to arrest him so he can escape the gang.

They take him away.

The French police are making hundreds of arrests like this, but despite the crackdown, they are, it seems, losing the war against a network of chaotic gangs that are starved to some extent by a growing army of brutalized children.

We've come down into the cellar now.

Police searching for places where drugs might have been hidden.

They find cocaine, hashish, traces of a drug industry now worth up to 7 billion euros across France.