Amnesty International has criticized Russian authorities for arresting and harassing critics in the run-up to Sunday's parliamentary elections.
The organization's program director for Europe and Central Asia, Nicola Duckworth, says Russia has created a climate in which it is difficult, if not impossible, to express dissenting views and report abuses.
The rights organization is calling for the release of opposition leader Garry Kasparov, who is serving a five-day sentence for leading a protest against Russian President Vladimir Putin.
The rights group also expressed concern about the November 22 attack by unknown gunmen on Farid Babaev, a political activist in the southern republic of Dagestan, and his death two days later.
Russian authorities deny the murder had any political motivation.
On Monday, President Bush said he was troubled by the Russian government's use of force to stop recent opposition protests, which he called peaceful. He also criticized Russian authorities for restricting journalists from reporting on opposition protests.
Some information for this report was provided by Reuters.