The internet monitoring group Turkey Blocks said on its website that the shutdown of Wikipedia is “consistent with internet filters used to censor content”.
In the past Turkish authorities have denied blocking internet sites, blaming technical problems instead.
But monitoring groups say the shutdowns are deliberate and often come after attacks, controversial government moves or demonstrations against the government.
Turkish users attempting to go to the Wikipedia page are receiving a message that the site cannot be reached, with a “connection timed out” notice, Euronews reported.
“After technical analysis and legal consideration … an administrative measure has been taken for this website (Wikipedia.Org),” the BTK telecommunications watchdog said in a statement on its website.
It cited a law that allows it to block access to individual web pages or entire websites for the protection of public order, national security or the well-being of the public.