The protesters were pushed back by officers, using water cannon and tear gas, police said.

Fresh clashes erupted early on Sunday in the streets of Hamburg following the end of the G20 summit, with protesters setting fire to a number of vehicles, police said.

Protesters gathered after the close of the summit in the Schanzen district, a stronghold for extreme-left radicals which has been the site of multiple confrontations since Thursday.

Armed with glass bottles and targeting vehicles, many of which they set on fire, the protesters were pushed back by officers, using water cannon and tear gas, police said on Twitter.

According to the most recent figures given by the police, some 213 police officers have been injured since Thursday, and 143 people have been detained. No accurate number for protesters injured is available.

President Frank-Walter Steinmeier visited wounded officers in hospital Sunday morning with Hamburg Mayor Olaf Scholz, saying he was "shocked and dismayed" by the "will to destroy shown by demonstrators against police and private citizens' property".

“We must ask ourselves as democrats whether a few violent protesters can keep countries such as Germany from holding such international meetings,” Mr. Steinmeier told reporters.

Mr. Scholz thanked the “heroic” police for their service and the citizens of Hamburg who brought flowers to a military hospital where many officers were being treated, pledging compensation for those who suffered losses from vandalism.

He dismissed criticism by some peaceful demonstrators that the police had been excessive in their crackdown and called for "lengthy jail sentences" for participants in the riots.

The explosion of violence at the meeting sparked pointed questions over how Hamburg could descend into “mob rule” and why Chancellor Angela Merkel chose a hotbed of leftist militancy as the venue.

Hamburg, a vibrant port city, is a citadel of anti-capitalist radicals and authorities had long been bracing for possible violence on the sidelines of the summit.

On Thursday, a planned peaceful march by around 12,000 people protesting against globalisation turned violent as a hard core of so-called black bloc masked anarchists attacked police and rampaged through city streets.

The German police officers' union GdP on Friday hit out at the black bloc, accusing them of "hijacking peaceful demonstrations by tens of thousands of people to deliberately attack" police.

The clashes occurred as leaders from the world's 20 biggest developed and emerging economies held a two-day meeting focusing on trade, terrorism, climate change and other key global issues.

World leaders made concessions on trade and climate language to US President Donald Trump on Saturday at the end of the most fractious and riot-hit G20 summit ever, in exchange for preserving a fragile unity of the club of major industrialised and emerging economies.