Russian authorities said Tuesday that several regional television and radio stations that have recently broadcast air raid alerts had been breached by hackers.
The alerts are common across Ukraine, which is routinely targeted by drone and missile attacks, but the impact of fighting within Russia is limited to regions bordering the conflict.
"As a result of hacking of servers of radio stations and TV channels, in some regions of the country, information about the announcement of an air raid alert was broadcast," Russia's emergencies ministry said in a statement.
"This information is false and does not correspond to reality," it added.
Russian media reported that the alerts had been broadcast in the Belgorod and Voronezh regions bordering Ukraine, near Moscow and St. Petersburg and on the Crimean peninsula annexed by Russia in 2014.
The emergencies ministry said a similar cyber attack last week triggered air raid sirens across Russia.
The hacks targeted only private radio and television stations.
The breaches came shortly after the first anniversary of Russian President Vladimir Putin's decision to send troops into Ukraine in February last year.
Several Russian regions bordering Ukraine have been targeted in attacks that Moscow has blamed on Ukraine.