Navalny's lawyers fear for his health, accuse Russian officials of blocking access

• Navalny is currently serving a 2.5-year prison sentence for allegedly violating his parole while recovering in Germany from an attempted poisoning, which he accuses Russian President Vladimir Putin of ordering.
• Navalny's lawyers returned to the prison on Thursday to attempt a visit, but it's not yet clear if they succeeded, according to Reuters.

The big picture: Navalny has been a fierce critic of corruption in Russia and has been described as "the man Putin fears most." His detention by Russian police in January sparked multiple weeks of protests, leading to thousands of arrests.

Details: Navalny's lawyers said that their client has been suffering from back pain and an unknown issue with one leg, which has gone numb, according to ABC News.

What they're saying: “In the circumstances that we are all aware of, the sharp worsening of his well-being cannot but cause extreme concern," his lawyers said in a statement.

• Russia's Federal Penitentiary Service denied these claims on Thursday, saying that a medical examination of Navalny had taken place and that he was "in generally good and stable health," according to CNN.