KIEV, Ukraine — The charges against Paul J. Manafort and an associate involve allegations of tax fraud in the United States, but anticorruption groups in Kiev say that Mr. Manafort profited from financial wrongdoing in their country and that it cost the Ukrainian people dearly.

“The arrest of Manafort is very positive, and a long-awaited event,’’ said Yaroslav Yurchyshyn, director in Kiev of Transparency International, which has been tracking money laundering in Ukraine for years.

The indictment, unsealed in Washington, on Monday accused Mr. Manafort of laundering $18 million and his associate, Rick W. Gates, an additional $3 million, taking advantage of a tangled skein of offshore companies and American real estate and home improvement deals.

Mr. Manafort and Mr. Gates pleaded not guilty to the charges.

Ukrainian prosecutors and courts have not pursued charges against Mr. Manafort. Unless they do that, Mr. Yurchyshyn said, it will not be possible for Ukraine’s government to claim assets in the United States possibly related to money laundered from Ukraine.