Dec 11 (Reuters) - Russian opposition politician Alexei Navalny has been removed from the IK-6 penal colony in the Vladimir region, east of Moscow, and his current whereabouts are not known, his allies said on Monday on social media platform X.

Navalny aides have been preparing for his possible transfer to a harsher-regime colony after he was sentenced in August to an additional 19 years in prison. (Reporting by Mark Trevelyan Editing by Gareth Jones)