MOSCOW, Sept 29 (Reuters) - Russia on Wednesday declared the OVD-Info protest monitoring group that played a major role in documenting anti-Kremlin demonstrations a "foreign agent", in the latest move of its kind that critics say is designed to stifle dissent. Russia has recently labelled several outlets "foreign agents", a legal designation used for what authorities say are foreign-funded organisations engaged in political activity. Russia"s justice ministry said it included OVD-Info media project in the list of "non-registered non-governmental organisations that act as a foreign agent". OVD-Info has for years covered anti-Kremlin street protests and offered legal support to those detained by police at such rallies. Among other individuals included in the expanded list are publishers of independent outlet Mediazone, editor-in-chief Sergei Smirnov and anti-Kremlin activist Pyotr Verzilov, who is an ally of jailed politician Alexei Navalny. The move comes as Russia"s tensions with the West in the media field are growing. Moscow on Wednesday threatened to block YouTube and the Kremlin called for "zero tolerance" towards the video hosting giant after it removed Russian state-backed broadcaster RT"s German-language channels from its site. read more The term "foreign agent" carries negative Soviet-era connotations and compels outlets to declare their status in disclaimers on their output, something they complain is akin to defacing their product and severely dents advertising revenue. Several Russian media outlets labelled as foreign agents have opted to shut down as finding sponsors and advertisers became almost impossible. The Kremlin rejects the idea that media are being persecuted and says the legislation is needed to protect Russia from foreign meddling and that journalists and NGOs can be manipulated.