"YouTube has blocked our RT Arabic with 5.5 million subscribers and almost three billion views. Looking into it", Simonyan wrote in her Telegram channel.
As of now, the broadcaster's account remains inaccessible.
In recent months, Russian media often find their social media accounts blocked.
In September, Twitter downgraded the search results’ status of the Russian state news agency RIA Novosti account. Twitter has previously done the same with RT and Sputnik accounts.
In December, Facebook blocked the account of the Baltnews website and in March it deleted an interview of RT France with an EU lawmaker from the National Rally party for alleged violation of its community standards.