Russia’s Digital Development Ministry said access to mobile internet would be restricted in Moscow on May 9 for security reasons during Victory Day events.
The ministry specifically warned that even services included on the government whitelist would be unavailable during the restrictions.
Some SMS-based services could also be disrupted, the ministry said.
Moscow had already experienced a large-scale mobile internet outage two days earlier during preparations for the parade. Similar warnings had been sent by mobile operators to residents of dozens of Russian regions.
The authorities did not disclose the technical mechanism behind the shutdown or explain which particular threats made it impossible to maintain whitelist access.
Mobile internet restrictions have become one of the principal measures Russian authorities use in an effort to interfere with drone navigation, although they also disrupt civilian infrastructure including payments, transportation, mapping, delivery services and communications.