The Kremlin is reportedly planning a campaign to sling mud at Alexei Navalny as they consider the opposition campaigner to be a serious political threat in next year's presidential elections.

Emerging from more than two weeks in jail for organising anti-corruption protests on 26 March, Navalny has been enjoying growing levels of popularity after targeting the alleged graft of prime minister Dmitry Medvedev.

Navalny released a film on YouTube alleging corruption of Medvedev and linking him to a luxury lifestyle and properties throughout Russia.

The claims have been dismissed by Medvedev. However, they have garnered 19 million views and the Levada Centre said these have led to a 10% drop in Medvedev's support.

Sources close to the Kremlin told the independent TV station Dozhd that a special team has been set up to generate material that will discredit Navalny, overseen by top officials Alexander Kharichev and Andrei Yarin.

It reported that the decision was taken by Vladimir Putin's deputy chief of staff, Sergey Kirienko.

The campaign against him may reportedly include "kompromat" and mudslinging similar to that organised against former prime minister Mikhail Kasyanov in 2016, whose parliamentary campaign ended after footage showed him cheating on his wife.

"They're filming videos, making viral clips, and designing little video games to discredit Navalny. They're fighting him like he's Hitler," a source told the station.

Navalny may not be allowed to run in the election as he has been convicted of embezzlement after a trial widely seen as trying to sideline him. However, the concern in the Kremlin is that even if he is not a candidate, he could taint the expected victory of Vladimir Putin.

Russian opposition leader Alexei Navalny attends a hearing after being detained at the protest against corruption and demanding the resignation of Prime Minister Dmitry Medvedev, at the Tverskoi court in Moscow, 27 March Reuters