A faked declaration of martial law and military mobilization by President Vladimir V. Putin of Russia aired Monday on a number of Russian radio and television networks, an incident that the Kremlin described as a “hack.”
The bogus speech, which was broadcast on the Mir radio station and television networks, said Ukraine had invaded three border regions and urged their residents to evacuate to the Russian heartland.
The clip also depicted Mr. Putin declaring a general mobilization, saying all the power of the country needed to be harnessed to defeat a “dangerous and insidious enemy.”
The press service of Mir, a Russian public broadcaster, said in a statement released to the state news agency Tass that its radio and television channels had been illegally interrupted for a little more than a half-hour before being restored.
It was unclear who was behind the fake speech. Dmitri Peskov, a Kremlin spokesman, told Tass that Mr. Putin “definitely” did not record any such emergency address and that an investigation was underway into what he called a “hack.”
The broadcast — which appeared to piece together genuine recordings of Mr. Putin’s voice to create a realistic spoof — coincided with a surge in Ukrainian attacks along the front line that may signal the start of Kyiv’s long-awaited counteroffensive.
The fake address — which claimed that the Ukrainian military had invaded three regions of Russia, including Belgorod — came after a series of attacks on Belgorod by militias aligned with Ukraine. The attacks, which have been claimed by two paramilitary groups made up of Russians who oppose the Kremlin, have prompted evacuations in some areas on Russian soil.
Alina Lobzina contributed reporting.