The United Nations criticized many “arbitrary arrests” of individuals protesting Russia’s invasion of Ukraine on Friday and called for their immediate release.

“Arresting individuals for exercising their rights to freedom of speech or peaceful assembly is an arbitrary loss of liberty,” said Ravina Shamdasani, a spokesperson for the UN Human Rights Office in Geneva.

“More than 1,800 demonstrators were apparently arrested,” she added, adding that the agency was aware of the situation. It’s unknown if any of them have been released.”

Her remark occurred a day after Russian President Vladimir Putin rejected Western warnings by launching a full-scale land invasion and air attack on Ukraine, which resulted in the deaths of hundreds of people and the displacement of at least 100,000 people.

Protesters took to the streets in cities all around the world, including Russia.

Police detained protestors in 51 places throughout Russia, according to an independent monitor, clamping down on dissent after officials cautioned residents against protesting.

“We demand that all people who have been arbitrarily jailed for exercising these rights be released immediately,” Shamdasani added.

The UN’s human rights director, Michelle Bachelet, said on Thursday that Russia’s incursion “obviously breaches international law” and “puts many civilian lives in jeopardy.”

“It has to be stopped right now,” she remarked.

She stated that her office will continue to keep a close eye on the issue and cautioned that “an information war is also taking place.”

“It is vital that we continue to rigorously monitor and seek to verify claims of human rights abuses, including civilian fatalities, damage to civilian objects, especially key infrastructure, and other impacts on human rights on the ground,” said the statement.