Bomb disposal teams were called after a suspect package was found at the entrance to RIA Novosti’s building in central Moscow on Wednesday afternoon.
“A suspicious box was found on the sidewalk,” a police officer said.
Dozens of staff have been evacuated.
Part of the Garden Ring, one of Moscow’s major thoroughfares, has been closed to traffic as a precaution.
Police said the suspected explosive device was discovered at 15:00 Moscow time.
The building also houses the Russia Today TV channel and The Moscow News newspaper.
The agency is located across the road from the Park Kultury metro station, which was targeted as part of a March 2010 suicide attack on the city’s metro system.