The loudspeaker message to the campers is clear: time for a final lesson, a strict female voice says, in sit-down protest.

“When you’re trying to block traffic, the golden rule is the fatter the better,” explains Agnès Bredouille, from Strasbourg, as she tries to persuade a corpulent man in leather trousers to attend the barricade seminar.

From today the ragamuffin army of up to 80,000 protesters on the north German coast will try to block the roads from Rostock airport to paralyse the G8 summit of world leaders.

For the protest movement, it is a critical moment. Since the rioting in Rostock on Saturday, when 1,000 people were injured, the protesters have been on edge. And their leaders are at loggerheads.

It’s Grrrrr8 (honest)

As the G8 summit begins in Germany, Hugo Rifkind explains everything you need to know – and lots of stuff you don’t

Multimedia

• Video: Our young man in Heiligendamm

• Audio: Behind the scenes at the G8

• Pictures: G8 summit

BACKGROUND

• Quotes: what Putin told The Times

• Blair reinvented the Middle Ages

• The West is starting this Cold War

• Save the planet: give to China

Related Internet Links

• Official site of the G8 summit Heiligendamm

Related Links

• Summit city pays price as protests turn nasty

• G8 activists turn peaceful demo into riot

So far, Attac, the anti-globali-sation network that claims to have 90,000 members world-wide, has been calling the tune: peaceful, disciplined protests aimed at the G8 leaders hiding behind a high steel fence discussing a common global future without consulting the masses. The message was weakened, however, the moment they seemed to lose control – when masked, black-clad youths broke ranks and set out to attack policemen.

The anarchists, known as the Black Bloc, are supposedly under the wing of a coalition calling itself the Interventionist Left (IL). The IL has not rushed to condemn the youths. “We should have reacted more quickly,” is as repentant as Tim Laumeyer, the IL leader, got.

The scope of the problem becomes obvious on visiting Camp Fischereihafen: this is a circus without a ringmaster.

There are 9,000 people in a site with facilities for 5,000 divided into “barrios”.

There are tent colonies occupied by Green activists, Catholic groups, the antifascists and Queers Against G8. A Clown Army has arrived with masks and make-up to mock and distract police while the more serious wire-cutting activists head towards the 13km (eight-mile) steel wall surrounding the venue in Heiligendamm. There are lectures on the evils of global capitalism and well-attended briefings on how to protect oneself against teargas.

The IL tries to keep its hold on its followers. Christoph Kleine, of the IL, threads his way through the tents, telling people: “The blockade of the airport is on, but no escalation! Don’t let yourself be provoked by the cops!” Yet it is an improvised organisation set up to combat G8, and has no natural following.

It is difficult to see then how the IL can hold back the Black Bloc thugs. They are scattered throughout the camp; without their signature face masks and sunglasses they are just spotty youths with tattoos, lingering over the collective lentil pot.

But their spokesmen occasionally appear and do not hide their contempt for other groups. “Those who keep on about the need for peaceful demonstrating are simply rendering themselves harmless,” a spokesman for the AntiFascist Left said. “That’s not a way to be taken seriously.”

The G8 summit begins tomorrow evening. The protests kicked off on Saturday with the aim of creating a carnival atmosphere. But the mood has curdled. The protest groups are caught in a power struggle. They wanted to turn the summit into a chaotic affair and claim it as a victory. It looks as if they may get the chaos but not the political triumph.

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