Video report from ITV News Correspondent Sejal Karia at Parliament Square
Thousands of protesters have taken part in anti-racism demonstrations in several UK cities this weekend, despite warnings from ministers that mass gatherings are banned.
Worldwide protests over the killing of George Floyd in Minneapolis are heading into their second weekend amid public anger at police over his death.
Unarmed African-American Mr Floyd died after a white police officer held him down by pressing a knee into his neck in Minneapolis on May 25.
Black Lives Matter protesters, the majority wearing masks and face coverings, gathered at Parliament Square in London chanting "no justice, no peace", before marching towards the US embassy.
After a largely peaceful protest throughout most of the afternoon, a small group clashed with police outside Downing Street shortly before 7pm.
Footage on social media show missiles thrown by police in protective gear, while mounted police tried to drive back some protesters along Whitehall.
One officer was knocked off their horse, which then bolted and sent crowds of people scattering.
Photographs showed the officer being treated as they lay injured on the pavement, while other images showed bikes being thrown at horses.
Superintendent Jo Edwards, spokesperson for policing today’s demonstration, said: “We understand peoples’ passion to come and let their voice be heard, they protested largely without incident.
“Our officers have been professional and very restrained but there was a smaller group intent on violence towards police officers."
She added: “Twenty-three officers have received injuries, doing their job, policing protest over the last few days, and that is totally unacceptable.
“There have been 14 arrests made today, but we expect that number to rise and there will be a post -event investigation carried out.”
Home Secretary Priti Patel said violence towards police at protests was “completely unacceptable” and gave officers her “full support in tackling disorderly behaviour”.
Writing on Twitter, she said: “Protests must be peaceful and in accordance with social-distancing rules.
“Violence towards a police officer is completely unacceptable at any time.
“The police have our full support in tackling any violence, vandalism or disorderly behaviour. There is no justification for it.”
Protesters vowed the demonstration would be peaceful after a previous protest earlier this week saw 13 people arrested amid physical clashes with police.
Boxing heavyweight champion Anthony Joshua used crutches to join people on a peaceful protest in his home town of Watford.
Many people wore face masks and social-distancing measures were encouraged during events in Manchester, Cardiff, Sheffield and Newcastle, among other cities.
Organisers urged protesters to keep demonstrations peaceful this weekend and those attending were asked to adhere to social distancing.
Professor John Edmunds, who attends meetings of the Scientific Advisory Group for Emergencies (Sage) supporting the government, said people attending should be “very careful”, wear face masks and observe social distancing rules.
It follows a warning from Health Secretary Matt Hancock at the government's daily coronavirus press conference that "we’re still facing a health crisis and coronavirus remains a real threat".
He said people should remember the rules, that they “should not attend large gatherings, including demonstrations, of more than six people”.
Black Lives Matter protests planned in UK this weekend:
London - Parliament Square, 1pm
Manchester - Piccadilly Gardens, 1pm
Newcastle Upon Tyne - Online 1pm
Leicester - Clock Tower, 1pm
Sheffield - Devonshire Green, 1pm
Ipswich - Town Hall, 2pm
London - US Embassy, 2pm
Manchester - St. Peter’s Square, 2pm
Edinburgh - Princes Street Gardens, 1pm
Glasgow - George Square, 2pm
Bristol - College Green, 2pm
Norwich - Haymarket, 2pm
Coventry - Godiva, 1pm
Derby - Derby Council House, 2pm
Colchester - Castle Park, 1pm
Mr Hancock admitted being "appalled" by the man's death at the hands of a police officer, but stressed "it is vital that people stick to the rules this weekend is to protect themselves and their family from this horrific disease".
An estimated 4,000 people are expected to attend a demonstration in Bristol, which will include a march through the city to Castle Park on Sunday, Avon and Somerset police said.
A protest planned in Newcastle was moved online after organisers said people should follow social distancing guidelines.
Home Secretary Priti Patel posted on Twitter, urging people not to gather in groups larger than six, "for the safety of all of us".
Amid warnings about social distancing, people have become more inventive with their protests, with many choosing to "take a knee", while remaining a safe distance from each other, at London’s Trafalgar Square.
But in the US tensions have oiled over between protesters and police and social distancing will not be possible in many US cities where hundreds of thousands are expected to attend.
Officials in Washington DC are expecting between 100,000 and 200,000 protesters on Saturday.
Dozens more protests are planned in cities right across America, from New York City to Los Angeles.
Protests were sparked after video footage showed Mr Floyd gasping that he cannot breathe while being arrested by four officers in Minneapolis, before being pronounced dead.
They have since been charged over the death which sparked days of protest in the US and Black Lives Matter (BLM) demonstrations across the world.