The decision was based on expertise conducted by leading Russian linguistic institutions, including the Linguistics Institute at the Academy of Sciences, Interfax reported.

In April, works by Scientology founder L. Ron Hubbard were added to a federal list of extremist materials on the decision of a Siberian court, which de facto rendered all Scientology centers open to prosecution.

The court's decision slammed Hubbard's books as inciting social and religious hatred, justifying violence, especially toward opponents of Scientology, and promoting anti-state views.

Former science fiction author Hubbard created Scientology in the 1950s. The secretive church has faced regular criticism and litigation from former members, who accuse it of being a cult charging massive fees for purported religious services.

Germany has ruled that it is a commercial organization, and several other European governments have refused to recognize it as a religion.

Scientology's branches in Surgut and Nizhnekamsk successfully sued the Russian government in October at the European Court of Human Rights for refusing to list them as religious organizations on the grounds that they had not existed in the country for 15 years.

In June, Samara region prosecutors reprimanded the head of a local telecommunications company, RosKabelSvyaz, for breaking extremism and labor laws by forcing subordinates to study Scientology under threat of dismissal. They cited the April decision of the Surgut court as the reason for the extremism accusations.