The powerful Chechen leader Ramzan Kadyrov has been taken to hospital with suspected coronavirus, according to Russian media reports.
Interfax news agency reported that he was receiving treatment in Moscow after developing flu-like symptoms.
His condition is unknown, although initial reports suggested his doctor had recommended he travel to the Russian capital.
The authorities in Chechnya have not confirmed or denied the reports.
The authoritarian leader is one of the most feared men in Russia, BBC Moscow correspondent Steve Rosenberg reports.
In the 1990s he fought against Moscow as a Chechen nationalist but now he is a key ally of Russian President Vladimir Putin.
Mr Kadyrov has imposed his own interpretation of Islamic law in the Caucasus republic, and has long been accused of serious human rights abuses.
According to Chechen data, at least 1,026 people have been diagnosed with Covid-19 in the Caucasus republic and 11 have died.