President Vladimir Putin has signed a bill which allows foreign non-governmental organizations (NGOs) to be banned from operating in Russia.

The new law allows the Russian authorities to prosecute foreign NGOs or companies 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 organizations deemed to pose a threat to the “foundations of Russia’s constitutional order, defensive capacity and security”.

Organizations linked to politics in Russia already face restrictions under a 2012 law requiring them to register as “foreign agents”.

The new bill’s supporters say it is essential to prevent Russia from outside interference, amid ongoing tensions due to the country’s involvement in Ukraine.

There was concern from Western governments and NGOs about the implications.

The US State Separtment said it was “deeply troubled” by the law.

State Department’s spokeswoman Marie Harf said in a statement: “We are concerned this new power will further restrict the work of civil society in Russia and is a further example of the Russian government’s growing crackdown on independent voices and intentional steps to isolate the Russian people from the world.”

Amnesty International said the bill would “squeeze the life” from civil society, while Human Rights Watch (HRW) warned it would be locals who would be worst-hit.