The Russian President Vladimir Putin has signed a bill which allows foreign organisations to be banned from operating in the country.
The law allows the authorities to prosecute foreign non-governmental organisations or firms designated as "undesirable" on national security grounds.
Individuals working for NGOs could face fines or up to six years in prison.
Critics say it is a Kremlin move aimed at stifling dissent.
The definition of "undesirable" is open to interpretation, but the Interfax news agency said it would apply to organisations deemed to pose a threat to the "foundations of Russia's constitutional order, defensive capacity and security".