Russia launched an investigation on Thursday into the country's chief independent election watchdog, in what the group described as the culmination of a state-sponsored campaign to silence the monitor just three days before parliamentary polls.
Moscow city prosecutors said in a statement the investigation followed a complaint filed by lawmakers objecting to watchdog Golos's foreign financing and calling for it to end vote monitoring.
The complaint echoed Vladimir Putin's speech on Sunday at his United Russia party congress, where he accused foreigners of funding his political opponents in what reminded some of the anti-Western rhetoric that marked his 2000-08 presidency.
Putin, now prime minister, is expected to easily recapture the presidency in March, but opinion polls show Sunday's vote could weaken his party's dominance in the lower house.
Golos employees told Reuters prosecutors had served the group with a speedy court order to hear its case on Friday.
This a premeditated campaign, which started with attacks in the press, but is now making use of law enforcement agencies, said Grigory Melkonyants, the deputy head of Golos.
We are certain this is only the first summons and there will be other investigations, especially targeted at hampering us from observing (the vote) on December 4.
Prosecutors could not immediately be reached for comment.
Golos, a non-profit organisation founded in 2000 whose name means voice in English, mans a hotline and has an interactive map where viewers can see campaign violations on the site kartanarusheniy.ru.
It openly says its funding comes entirely from Europe and the United States and maintains that helps it be objective.
Melkonyants read from documents in which prosecutors warn the organisation of breaking election laws by spreading falsifications and rumours.
Days before the vote, over 3,000 alleged campaign violations were on Golos' website, many of them including videos which have embarrassed United Russia officials.
One video clip that has become popular on the Internet showed a top official in the western Urals city of Izhevsk telling veterans they would get money if they voted for the United Russia party.
It prompted rare punishment from authorities, and the city official was found guilty by a Russian court and fined.
Trouble for Golos began on Saturday, when reporters from the Kremlin-friendly TV station NTV barged into its offices, Melkonyants said, shouting and asking questions about the watchdog's financing.
On Wednesday online news portal Gazeta.ru removed a link to Golos' website, prompting one of its deputy editors, Roman Badanin, to resign over what he dubbed an amoral decision.
Tanya Lokshina of the Moscow branch of New York-based Human Rights Watch said the incidents were part of a smear campaign directed at getting rid of the organisation altogether.
They are trying to shut it up because Golos is the only large-scale, serious organisation that is exposing election violations, she told Reuters.
(Reporting by Alissa de Carbonnel; Additional reporting by Maria Tsvetkova; Editing by Sophie Hares)