Russian news agencies report that Russia will block Twitter in one month unless the social media giant complies with a demand to remove banned content.
Moscow said last week it had slowed down the speed of Twitter inside Russia in retaliation for what it described as a failure to remove a specific list of banned content.
Twitter said at the time that it was worried about the impact on free speech of the Russian action.
It denied that it allowed its platform to be used to promote illegal behavior as alleged by Russian authorities.
In a move that escalates the growing stand-off, Vadim Subbotin, the deputy head of Roskomnadzor, the communications watchdog, was cited as saying Tuesday that Twitter had not addressed Russian concerns yet and would be blocked in Russia in a month unless it did so.
He was quoted as saying that Twitter could still avoid being blocked if it took action to delete the banned content, which Moscow has said includes child pornography and material on illegal drugs and child suicide.
Twitter did not immediately respond to a request for comment.