The penal colony where Kremlin critic Alexei Navalny has been sent to serve his two-year sentence is "one of the worst" in Russia, former inmates and prisoners rights groups have said. Mr Navalny was reported to have arrived at penal colony No. 2 in the town of Pokrov, three hours outside Moscow, on Sunday. Transfers of inmates within Russia's penitentiary system can take days or weeks and relatives often only discover the whereabouts of a prisoner after he or she has arrived at a prison. Mr Navalny’s arrival has not yet been confirmed by his legal team and he could be moved again. Former inmates of colony No 2 told the Telegraph that if Mr Navalny stays at the prison he will be subjected to a combination of intense isolation and gruelling psychological and physical pressure designed to mentally destroy him. “It’s one of the worst colonies in Russia. Former inmates are afraid to speak out about the conditions because they risk repercussions after they leave the prison,” said Ruslan Vakhapov, a human rights activist who specialises in defending prisoners for local NGO Jailed Russia. “Navalny will probably be isolated from the outside world and other prisoners will be prevented from talking to him,” Mr Vakhapov said. Prisoners face abuse by prison guards if they violate a strict schedule, he said, while the colony administration encourages prisoners to control and monitor other inmates. “There are no rights for prisoners in Russia,” Mr Vakhapov said. “Navalny faces immense pressure that can psychologically weaken him, but I think the administration will be afraid of using physical force on him. It could damage their reputation completely,'' he added.