Anti-capitalist protestors plunged the start of the G20 summit in Hamburg into chaos on Friday as they blocked the streets leading to the venue.
Protestors attacked a police helicopter with a firework, set dozens of cars alight and tore down street signs to barricade the roads. Police responded with water cannon and baton charges.
Melania Trump was blocked by protestors from reaching an event organised for the spouses of leaders on Friday.
Angela Merkel's husband, Joachim Sauer, was hosting the spouses. But a spokesman for the US delegation said they had been unable to get security clearance for Ms Trump to travel to the event.
"We have no security clearance from the police to leave the guesthouse," Mrs Trump's spokesperspon told German media.
A Hamburg police spokesman told The Telegraph that they had "no reports of any protest incident in the area of the Trump guest house".
However, they could not confirm or deny whether there was a security threat to Mrs Trump.
Malcolm Turnbull, the Australian prime minister, tweeted that he was under “security lockdown” with the Indonesian president, Joko Widodo. Police guarding the hotel where Mr Turnbull is staying briefly came under attack by protestors at one point.
Meanwhile a car belonging to the Canadian delegation had its tyres slashed by protestors
Observing security lockdown at G20 in Hamburg with @jokowi. Good opportunity to have an extended meeting between two close friends
5:16 AM - 7 Jul 2017
A press conference by EU representatives Jean-Claude Juncker and Donald Tusk started 45 minutes late amid reports that they had been delayed by the chaos on the streets.
And Wolfgang Schäuble, the German finance minister, had to pull out of a meeting because he could not reach the venue, according to organisers.
Demonstrators on Friday in Hamburg CREDIT: STEFFI LOOS/AFP/GETTY IMAGES
But Donald Trump made it to the summit on time, driving through the city at high speed under heavy police escort.
But the authorities were accused of a heavy-handed response, with a joke doing the rounds on Twitter that the Hamburg police were trying to make Turkey’s President Recep Tayyip Erdogan feel at home.
As Angela Merkel welcomed leaders to the conference centre where the summit is being held, outside protestors attempted to stage a sit-in.
They dragged police barricades out of place to set up their own roadblocks, and let off green smoke bombs.
German riot police walk next to a police vehicle during a rally outside Schlump station CREDIT: EPA/ARMANDO BABANI
Riot police forced the protestors out of the street, in some cases dragging them out bodily.
A woman in a blue smock hung limp as polic dragged her along the ground by her arms. Officers picked up two young men with masks and threw them onto the pavement.
Eventually the water cannons were moved in, and the protestors dispersed.
Police and protesters clash outside G20 summit
A firework hurled at a police helicopter by protestors narrowly missed, police said.
All weddings scheduled to take place today in central Hamburg have had to be called off after the registry office was forced to close because of the security situation.
Police are already calling for backup as the violence rages CREDIT: EPA/FILIP SINGER
These were not the scenes Mrs Merkel wanted when she decided to hold the G20 in central Hamburg. The word is that she wanted to show that an advanced democracy permits peaceful protest.
Instead the images that will go around the world are of heavily armoured police shoving protestors out of the way, and the comparisons with Mr Erdogan’s Turkey.
This is not the image Mrs Merkel was hoping to show the world CREDIT: EPA/MASSIMO PERCOSSI
Hamburg police said on Friday morning they have sent an urgent call to other forces across Germany for reinforcements, despite the fact there are already 15,000 officers on the streets.