Alexei Navalny during a court hearing in September
Kremlin critic Alexei Navalny has confirmed his arrival at an Arctic prison and said he is in good spirits.
His team had had no contact with him since 6 December, after he was moved from another jail to the east of Moscow.
But on 25 December Navalny’s spokeswoman, Kira Yarmysh said that he had been found.
Considered Vladimir Putin’s most vocal opponent, he has been imprisoned since 2021.
Navalny confirmed on Tuesday that he had been moved to the IK-3 penal colony, nicknamed “Polar Wolf”, in the northern town of Kharp, some 1,900km (1,200 miles) northeast of Moscow.
IK-3, in the Yamalo-Nenets autonomous district, is seen as one of the toughest jails in Russia and most detainees held there have been convicted of serious crimes.
Writing on X, formerly known as Twitter, Mr Navalny said he had been transported with “such precaution” and along “such a strange route” that he was surprised when he was told that his lawyer was there to see him, as he did not think he would be found before “mid-January”.
Navalny had previously been held in Melekhovo, 235 km (145 miles) east of Moscow. He is facing a 19-year jail term, for founding and funding an extremist organisation – accusations he has always denied.
He suggested he had been moved first to the capital, then east to the Urals mountain region and again to the west, before being moved north of the Arctic Circle.
The US said that while it welcomed reports that Mr Navalny had been located, it remained “deeply concerned” about his wellbeing and conditions of detention.
Ms Yarmysh said Russian authorities were intent on isolating Mr Navalny and “trying to make his life as unbearable as possible”.
“This colony is very distant, it is very difficult to access it and for lawyers, it will be very difficult to go there and to see Alexei,” she added.
Navalny’s aide Ivan Zhadov said the change of prison demonstrated how “the system deals with political prisoners, trying to isolate and suppress them”.
His team had grown increasingly worried after he failed to appear at several court hearings.
Mr Navalny made his name as a campaigner against corruption, gathering millions of views for his video investigations.
A charismatic campaigner, he seemed to be the only Russian opposition leader capable of mobilising people in large numbers across Russia to take part in anti-government protests.
But in 2020, he was poisoned in Siberia by what Western laboratories later confirmed to be a nerve agent.
He was treated abroad. On returning to Russia in January 2021, he was immediately arrested.
Mr Navalny maintains a presence on social media with help from his staff and lawyers.