Eight police officers have been injured as anti-lockdown protests in central London turned violent.
Demonstrators hurled bottles as officers attempted to disperse the crowds in Hyde Park this evening, the Metropolitan Police said.
Photographs posted on social media show a female police officer bleeding from a cut to her head, while another suffered a similar wound on his forehead.
The protests, which also took place on Oxford Street, come almost two weeks after Covid-19 lockdown restrictions were eased in England.
Five people were arrested for offences including assault on police and remain in custody, the Met said.
Two officers who were taken to hospital are not believed to have suffered serious injuries, the force added.
John Apter, national chairman of the Police Federation of England and Wales, tweeted: "These officers are just doing a job, they're somebody's son, daughter they're mums and dads.
"To be targeted in the way they are says a lot about the society we've become."
Demonstrators held banners with messages such as: "Covid-19 Vaccine Holocaust", and: "No To Vaccine Passports."
Another banner read: "You don't need proof to know truth."
Earlier in the day, the Met said a 38-year-old man was arrested near Embankment on suspicion of a public order offence, while a 37-year-old man was arrested near Trafalgar Square on suspicion of being drunk and disorderly and a public order offence.
The force said both men had been taken into custody as inquiries continue.
A British government review into "Covid status" certificates has said they could "potentially play a role" in settings such as theatres, nightclubs and mass events, and might also be used in pubs and restaurants to reduce social distancing restrictions.
The documents would record whether someone has had a vaccine, a recent negative coronavirus test or natural immunity, having recovered from Covid-19.