In scenes reminiscent of a war-zone, Hamburg has been plagued by arsonist thugs setting vehicles alight, with video showing scores of cars burning out across the city.

Violent clashes have broken out between anti-capitalist protesters and German riot police on day one of the meeting of world leaders.

The protesters reportedly stormed a cordoned off area close to the summit venue – just hours before world leaders were due to meet.

A signal flare was fired at a police helicopter and a police station was firebombed by "perpetrators of violence" this morning as unrest grips the city.

Hundreds of masked, black-clad protesters were also filmed from inside a Hamburg bus storming down the street.

Hamburg Police have reportedly called for "all available forces" as "many crimes" are being committed in spontaneous protests that risk becoming a “danger to life and limb”.

Other peaceful protest groups are staging sit-ins across the city in demonstrations against Donald Trump, Vladimir Putin and Turkey's Recep Tayyip Erdogan.

(Image: GETTY )

Welcome to hell: Hamburg BURNS in violent clashes ahead of G20 summit View gallery

(Image: GETTY )

(Image: GETTY )

Some groups of protesters are said to be planning to siege restricted areas of the summit venue throughout the day, CNN understands.

Protesters from the "Color The Red Zone" told CNN they want to block world leaders from getting to the venue, Hamburg’s trade fair and congress centre.

Dozens of protests have already reportedly attempted to block cars from accessing the summit, which is now underway.

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One protester, who did not wish to be named, said: “We are living in a democracy and the red zone is not a democracy.

"I'm sure we can't stop all these leaders from meeting but if we can stop them from getting their food or catering shortly we've achieved something.”

(Image: GETTY )

(Image: GETTY )

Around 20,000 police from all of Germany's 16 states are preparing to face a 100,000 strong group of anarchist protesters over the weekend.

Today's scenes of chaos come after at least 111 police officers were injured in violent clashes with thousands of protesters last night as world leaders arrived in Hamburg.

Hamburg Police said 44 people were arrested but it is not known how many were injured.

(Image: GETTY )

Thugs wearing balaclavas threw smoke bombs, lit fires and threw bottles at officers, who responded with water cannons and pepper spray.

Prime Minister Theresa May is among world leaders set to meet at the summit amid the mass hard-left “Welcome to Hell” demonstrations.

Us President Trump and Russian lleader Putin are also set for their first face-to-face showdown in a meeting that could change the world.