Ten days of Extinction Rebellion demonstrations in London ended with naked protests and an arrest over graffiti daubed on a statue of Sir Winston Churchill.

At least 648 people have been arrested during the environmental action, including one man on Thursday on suspicion of causing criminal damage to the statue of the former prime minister in Parliament Square.

Yellow graffiti was daubed on its plinth, including the words “is a racist”.

London mayor Sadiq Khan said: “This appalling vandalism is completely unacceptable. It will be fully investigated and the statue will be cleaned as quickly as possible.”

The Metropolitan Police confirmed protesters had dispersed after 7pm, in line with conditions imposed on the event.

Earlier, a group of semi-naked protesters who chained themselves to railings surrounding Parliament in a bid to expose what they called the “bare truth” about the climate crisis were arrested.

At least 13 topless women attached themselves to the outside of the Palace of Westminster, with bike locks around their necks.

They were part of a larger group from the XR campaign, which have used attention-grabbing techniques to highlight their concerns about the threats facing the planet.

The women wore masks with “4C” written on them, and with words including drought, starvation and wildfires written on their chests to highlight the anticipated consequences of global warming.

A banner read: “Can’t bare the truth?”

Sarah Mintram, a teacher who took part in the action, said: “Now we’ve got your attention. By neglecting to communicate the consequences of a 4C-world – war, famine, drought, displacement – the Government are failing to protect us.”

Officers removed the D-locks from their necks and took the women to police stations in four vans as supporters cheered them on.

Although the XR protests have won some public support as they marched on cities across the UK in the past year, Home Secretary Priti Patel has described the activists as “so-called eco-crusaders turned criminals”, and pledged to prevent “anarchy on our streets”.

Prime Minister Boris Johnson also criticised their “completely unacceptable” action in blocking the delivery of some of the UK’s major newspapers earlier in the week.