Russian opposition leader Alexei Navalny has been transferred to the Vladimir region, some 200 kilometers east of Moscow.
There he has to serve his 2.5-year sentence in a penal colony, reports Russian media.
Navalny's followers and relatives are said to have spent days in the dark about his location.
They were not told where he had been taken.
The Russian prison service had only confirmed that he had been sent from a Moscow detention center to a penal colony, without going into details.
A member of the committee overseeing the treatment of prisoners shared additional information on Sunday.
He told Interfax news agency that Navalny had been sent to Vladimir.
"He must first be quarantined. Then he goes to his colony," said the official.
Navalny's conviction has sparked street protests in Russia and international criticism.
President Vladimir Putin's well-known critic had been poisoned in his home country last year and transferred to Germany for medical treatment.
Authorities arrested him when he returned to Moscow.
He would not have adhered to the conditions for a suspended prison sentence.
He must therefore still sit it out.
'Life and health of Navalny are not endangered'
The head of the prison service emphasized last week that Navalny will serve his sentence under "normal circumstances".
"I can guarantee that his life and health are not endangered," said Alexander Kalashnikov.
In the camp, prisoners are housed in barracks.
An opposition activist imprisoned there for a year and a half told
that he faced constant harassment.
For example, he was punished if he did not greet guards and if he borrowed gloves from someone.
Gloves that his own family sent did not reach him.
"Alexei is going to have a really tough time," predicted activist Konstantin Kotov.
He said he had faced "tremendous psychological pressure" from his first day at the camp.
His lawyer agreed.
"If I was on the prison duty and I wanted to make Navalny's life as hard as possible, that would be exactly the camp I would send him to."