Ukrainian news site UkraNews.com reported on the studio's closure earlier today. Initially, the firm's Twitter account denied the closure, but the tweet has since been removed.
GSC studio director Dmitri Bourkovski later confirmed the news by simply tweeting: "[translated from Russian] Not PR. GSC closed."
GSC Game World was best known for its post-apocalyptic survival S.T.A.L.K.E.R. series, which included Shadow of Chernobyl, Clear Sky and Call of Pripyat.
S.T.A.L.K.E.R. 2 was announced in 2010, but with the studio's closure it is no longer under development.
In 2006, the studio 4A Games was formed by former GSC Game World developers. Last year, 4A Games launched Metro 2033, with the sequel Metro: Last Light scheduled for a 2012 release.