According to his associates, Alexei Navalny, a jailed Kremlin critic, has been transported to an undisclosed location.

Kira Yarmysh, the spokesman for the imprisoned Russian opposition leader, stated that the move created concerns for his safety.

Mr. Navalny has been open in his opposition to President Vladimir Putin, and in March, he was sentenced to nine years in prison for large-scale fraud and contempt of court.

US Secretary of State Antony Blinken earlier dismissed the claims as doubtful.

After further accusations were filed last month, it was stated that he faces "up to 15 more years" in prison.

On Tuesday afternoon, Ms. Yarmysh stated on Twitter that there were rumors that Mr. Navalny would be transferred to a high-security penitentiary colony but that it was hard to tell if or when he would arrive there.

She said, "The issue with his relocation to a different colony is not merely that the high-security colony is far more terrifying.

As long as we don't know where Alexei is, he stays alone with the system that has already attempted to kill him, so our priority is to locate him quickly.

Mr. Navalny, born in the then-Soviet Union near Moscow, has long been Mr. Putin's most outspoken adversary in Russia.

In June of 2012, a Russian court declared organizations associated with Mr. Navalny to be "extremist" and outlawed them.

He has spoken against the Ukraine war, describing the invasion as "stupid" and "built on lies."

While serving his prison term, he urged fellow residents to hold daily demonstrations.

In January 2021, he was detained upon returning to Russia from Germany, where he had recuperated from nerve agent poisoning.

The Russian opposition leader fell unwell during a flight to Moscow and was later determined to have been poisoned with novichock during a Siberian campaign trip.