MOSCOW -- A prominent Russian human rights advocate said he was kicked and beaten during a forcible eviction before dawn on Saturday that came amid mounting pressure on civil society groups that publicly criticize the government.
Lev A. Ponomaryov, 71, said he was dragged across the floor and kicked by men in civilian clothing while riot police officers watched. He said that paramedics found "more than a dozen bruises, scratches and other marks" when he received first aid afterward.
The authorities said the lease for Mr. Ponomaryov's organization, For Human Rights, whose building is owned by the city government, had expired in February and was terminated last month.
A Moscow police spokesman said Saturday that the mayor's office had ordered the eviction, which followed a raid that began late Friday. The spokesman said that the police "did not take any forcible measures," and that the eviction was carried out by a private security company.
Late Saturday, Mikhail D. Prokhorov, a billionaire and former presidential candidate, offered to pay the organization's rent, telling the Interfax news service, "I personally know Lev Ponomaryov and sincerely value the work that he does."
Mr. Ponomaryov, a former member of Parliament whose activism dates to the Soviet period, has been vocally defiant in recent months as President Vladimir V. Putin has taken steps to uproot organizations like For Human Rights that receive financial support from the West. Mr. Putin has said Western governments tried to stir up antigovernment protests with the help of Russian nonprofit groups.
Mr. Ponomaryov said he believed the raid had been approved by Putin administration officials. He said that he had never received official notice that his lease was to be terminated and had expected Moscow to extend it, as in previous years.
"I think there is a purge going on, Putin has untied his hands, and there is no reaction at all from the West to the fact that he is behaving this way," Mr. Ponomaryov said, adding that the use of force in the raid was unusual because it occurred in public.
"Usually, if they beat us, it happens inside, like in the back of a paddy wagon," he said. "It is secret -- no one knows, no one sees. And here, there were 20 people standing in the room. These people beat me publicly, and they were employees of the mayor's office."
The United States ambassador, Michael A. McFaul, criticized the eviction in a Twitter comment, calling it "another case of intimidation of civil society." Freedom House, a democracy watchdog organization, released a statement describing the raid's "thuggish tactics." It said that "people were thrown to the ground and violently beaten" but that the police refused to intervene.
Russia's human rights commissioner, Vladimir Lukin, told Interfax that he was "saddened and alarmed" by the incident, and that he was denied access to the building on the night of the raid, which he called "a gross violation of federal constitutional law."
"Officials from the Moscow administration, the Interior Ministry and apparently some other organizations were trying to settle a dispute between the two bodies unilaterally, without judicial bodies, and therefore arbitrarily," Mr. Lukin said. The Kremlin's Human Rights Council has called a special meeting next week to discuss the episode.
Several dozen journalists and activists picketed during the day, displaying signs that read, "We will not give up" and "Riot police are morons."
Mr. Ponomaryov was the victim of a beating in 2009, when a group of men ambushed him outside his home. More recently, after Mr. Putin backed a measure requiring nonprofit groups receiving Western support to register as foreign agents, the words "Foreign Agent" were spray-painted on the front door of his office.
Anna Tikhomirova contributed reporting.
This article originally appeared in The New York Times.