By Andrew Osborn and Tom Balmforth
MOSCOW (Reuters) - Russia declared investigative news outlet "Proekt" on Thursday an "undesirable" organisation on national security grounds and banned its activities, in the latest blow against media which look into areas the authorities say are off-limits.
The move is part of a wider crackdown ahead of September's parliamentary election on media seen by the authorities as hostile and foreign-backed. Proekt has published a series of deeply researched and unflattering investigations into Russia's ruling elite.
In a statement, the General Prosecutor's Office said Proekt's activities constituted a "threat to constitutional order and security". It described the outlet as a U.S.-based non-governmental organisation.
Roman Badanin, Proekt's editor-in-chief, described the move as the best possible proof that his outfit was doing good work, adding that it was not going anywhere. He did not elaborate further in a Facebook post reacting to the designation.
Authorities on Thursday also labelled eight journalists as "foreign agents", including reporters from Proekt, as well as the Open Media outlet, the Interfax news agency reported.
The decision to declare a media outlet undesirable appears to be a serious escalation of the crackdown against media the authorities see as hostile.
The justice ministry lists 40 groups that have received the same designation. None of them are media outlets.
Under a 2015 law, members of "undesirable organisations" can be fined or jailed for up to six years for ignoring the ban.
The Kremlin has previously denied that any media crackdown is underway and has described Russia's media market as vibrant with many different outlets to choose from.
Proekt came under pressure last month when police raided the homes of two of its journalists and detained a third as part of a criminal investigation into suspected slander.
Police seized laptops and other property from the homes of Badanin and Proekt reporter Maria Zholobova. Its deputy editor-in-chief, Mikhail Rubin, was also detained.
Several non-state outlets have complained of mounting government pressure in recent months.
Online news site Newsru announced its closure earlier this year for economic reasons, saying that advertisers were steering clear of it because its story selection did not follow pro-Kremlin state media.
News website VTimes announced its closure last month after being labelled a "foreign agent", a designation it said had scared away its partners, ruined its business and made it harder to report the news.
Radio Free Europe/Radio Europe has been fined heavily for refusing to comply with a rule requiring it to publish disclaimers on its content saying it fulfils the function of a foreign agent.
Latvia-based independent outlet Meduza has also been labelled a foreign agent.
(Additonal reporting by Polina Devitt, Anton Zverev, Polina Nikolskaya; writing by Tom Balmforth; editing by William Maclean and Gareth Jones)