Russian President Vladimir Putin signed into law on Saturday new measures allowing authorities to list foreign media outlets as "foreign agents" in response to what Moscow says is unacceptable US pressure on Russian media.

The new law has been rushed through both Russian houses of parliament in the last two weeks. It will now allow Moscow to force foreign media to brand news they provide to Russians as the work of "foreign agents" and to disclose their funding sources.

A copy of the law was published on the Russian government's online legislation database on Saturday, saying it entered into force from the day of its publication.

Russia's move against American media is part of the fallout from allegations that Russia interfered in last year's US presidential election in favour of Donald Trump.

US intelligence officials have accused the Kremlin of using Russian media organisations it finances to influence U.S. voters, and Washington has since required Russian state broadcaster RT to register a US-based affiliate company as a "foreign agent".