Demonstrators aiming to bring Brixton to a halt stopped traffic by blocking main roads on Saturday, despite police imposing restrictions in the area.
Hundreds of people have gathered in south London for the seventh Afrikan Emancipation Day March.
A large crowd has now stopped traffic and forced motorists to turn around while marching on the A23 Brixton Road.
It comes after a coalition of groups including Afrikan Emancipation Day Reparations March Committee, Rhodes Must Fall Oxford, and Extinction Rebellion warned they would block the A23 Brixton Road from Max Roach Park to Windrush Square and occupy the area for the day.
Organisers planned to shut down a major road through the centre of Brixton in protest against a lack of action on the issue of reparations for slavery.
On Friday Scotland Yard said that, while the majority of attendees would be congregating for a “family-friendly, socially distanced day of activities and learning”, it was imposing an 8pm curfew and other restrictions on the event.
Crowds of people listened to music in Windrush Square – where the event began – watched speeches and observed a three-minute silence to mark the event, which is in its seventh year.
Held on August 1, it marks the passing of the 1833 Abolition of Slavery Act, according to organisers.
A coalition of groups were involved in the event on Saturday, including Stop The Maangamizi: We Charge Genocide/Ecocide, the Afrikan Emancipation Day reparations march committee and the Rhodes Must Fall Oxford campaigners.
Protesters, floats with speakers and people on motorbikes spilled out onto Brixton Road shortly before 4pm and began to march to nearby Max Roach Park.
Antoinette Harrison, who lives in nearby Clapham, praised the “unity” of the event as she marched with her cousin and cousin’s children.
On why she chose to join, the 38-year-old said: “We are tired. And I was just saying, our parents have gone through, we’re going through this, and I don’t want our next generation to. It’s got to come to an end.”
She added: “What’s lovely about it is there’s such unity.
“It’s not just the one race, like it was back in the day, now it’s whites, blacks, Hispanics – everyone.”
Asked if she had any concerns about Covid-19 while attending, Ms Harrison, who has been protesting since earlier in the summer, said: “This is a pandemic – racism and not having justice.”
A large number of Metropolitan Police officers observed the event, with some attempting to move demonstrators, many of whom were wearing masks, off the road and onto the pavement.
Ahead of the demonstration, the force said blocking the road would cause “serious disruption” to Brixton and the surrounding area because it is used by hundreds of bus routes and thousands of motorists.
A number of conditions were imposed on the demonstrations within areas such as Windrush Square and outside Brixton Police Station, stipulating that attendees must not spill into nearby roads and any event must finish by 8pm.
The Metropolitan Police said that the time limit was set so that officers could separate those attending the demonstrations from people attending other gatherings or unlicensed music events.
It also said that gatherings of more than 30 people will be in breach of the Health Protection (Coronavirus) Restrictions and its decision to impose conditions did not mean the assembly in breach of these regulations was authorised by police.