Alexei Navalny is a Kremlin critic who was poisoned in 2020.
Russia's Prosecutor General said the activities of Bellingcat its partner The Insider "posed a threat to... the security of the Russian Federation."
When his lawyer arrived at Correctional Colony No. 2, a prison camp in Pokrov, 119 km (74 miles) east of Moscow, he was told: "There is no such convict here."
Following the invasion of Ukraine, the Kremlin has accelerated its decades-long campaign to quash and silence Russia's domestic opposition.
Navalny was appealing against a nine-year jail sentence he was handed in March for fraud and contempt of court.
Alexei Navalny will now be moved to a more remote facility. It's unclear when or if he will appear in court or have any communication with his lawyers, who were detained.
Prosecutors had asked the court to send him to a maximum-security penal colony for 13 years on charges of fraud and contempt of court. A ruling is expected later on Tuesday.
Violetta Grudina was barred from standing for election last year in the Arctic port city of Murmansk.
The UN human rights office said Russian courts had decided to 'dissolve two of Russia’s most respected human rights groups and further weaken the country’s dwindling human rights community.'
With just 9% of ballots counted nationwide, the Central Election Commission said United Russia had won 38.57% of the vote.
From his prison cell, Alexei Navalny called on world leaders, namely US President Joe Biden, to show "real decisiveness in the fight against corruption."