Russian Foreign Minister Sergei Lavrov Monday called reports that Defense Minister Sergei Shoigu has suffered a heart attack an "outright lie" being spread by Ukraine and "Russian neo-liberals," but another report indicates that both Shoigu and Russian President Vladimir Putin could be staying in their nuclear bunkers.

"I don't want to comment on nonsense, because this is precisely nonsense that is being spread by the Ukrainian special services and our Russian neo-liberals, who are now abroad," Lavrov said in an interview with the Serbian media about the reports on Shoigu, according to Russian state media outlet Tass. "This is all an outright lie. Everyone is alive, healthy."

Lavrov's comments were also reported through the Russian news service Regnum, saying he had made the "announcement" on Monday.

Shoigu had not been seen in public between March 11 to March 24, when he was shown briefly in a video released by Putin.

The defense minister also appeared in a video Saturday where he was shown chairing a meeting calling on the Russian Finance Ministry to allow for more cash for the war, reports The Daily Mail.

Anton Gerashchenko, the adviser to the Minister of Internal Affairs of Ukraine, claimed in a Facebook post Saturday that Shoigu suffered a heart attack. There have also been reports that security was tightened around Shoigu, 66, because of assassination threats, but other reports say he's been complaining about his health.

Meanwhile, Bulgarian journalist Hristo Grozev, of the Netherlands-based investigative journalism site Bellingcat, reported in a Russian-language interview this weekend that Shoigu is in his nuclear bunker in Ufa and that Putin is in his own bunker in the Altai region in Siberia.

Grozev, the lead Russia investigator with Bellingcat, said he came to his conclusions after studying the Kremlin airplane pool's flight data.

He noted that the Russian planes haven't been shutting off their transponders, except for the Altai flights in the "last half-hour of flight," and called that a "transparent" action to send a signal to the West.

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