He looked gaunt and weak, his skin stretched tightly over his skull. Video of jailed Kremlin critic Alexei Navalny that emerged in late April has focused attention on a Russian prison system that, former inmates say, is designed to break convicts, not reform them, and where medical neglect is rife.

Navalny had just ended a 24-day hunger strike when he appeared by video link at a Moscow court hearing, his latest skirmish with Russian prosecutors. His refusal to eat was in protest at the prison authority's refusal to allow an outside specialist to treat him for back pain.

Navalny's ordeal is nothing out of the ordinary, say seven people familiar with the IK-2 Male Correctional Colony east of Moscow, where in March he began a two-and-a-half-year sentence for parole breaches. If anything, these people say, Navalny's political celebrity may be protection from the violence that many other convicts endure.