Russian authorities seem to have launched a "witch hunt" against activist groups that is damaging the country's path to democracy, a top US official said Thursday.

Washington is concerned by an "unprecedented" wave of raids on at least 100 top Russian and foreign non-governmental organizations (NGOs), State Department spokesman Victoria Nuland said.

"These inspections appear to be aimed at undermining important civil society activities across the country," she told journalists.

"The sheer scope of these inspections now... really gives us concern that this is some kind of a witch hunt," she said, highlighting that religious and educational organizations exempt from strict new laws on financing were also being targeted.

Rights activists have linked the searches to the controversial law forcing foreign-funded NGOs involved in politics to carry a "foreign agent" tag.

"These laws are extremely restrictive," Nuland said, adding that "they are chilling the environment for civil society, which is taking Russian democracy in the wrong direction."

Even though Moscow kicked out the US Agency for International Development last year, the United States was still working from the outside to provide aid to those groups inside Russia who wanted to work with them.

Nuland would not go into details, fearing it would "endanger the programs and the receiving organizations."

Washington has also raised its concerns over the inspections and the new laws with Russian leaders, she added.