The controversial atheist blogger who is in custody in Russia after he filmed himself playing Pokémon Go in a landmark Russian Orthodox Cathedral could face a further four years in jail, it has been revealed.

Ruslan Sokolovsky has been remanded in jail for two months and is already facing five years in jail if convicted of extremism, disrespect and insulting the feelings of believers. His YouTube video of playing the augmented reality game in the cathedral has had more than 1.1 million views. The charges of "preventing the realisation of the right to freedom of conscience and religion and incitement of hatred" were laid against him on 3 September.

Investigators who searched his home announced yesterday they discovered a "spy pen" for recording videos, which could lead to a further four years in prison on additional charges, 9News reported. In the video, the blogger swears, ostentatiously plays the game in front of the Orthodox icon screen and holy candles, and even compares Jesus to a Pokémon.

The case has drawn international attention.

Amnesty International said said his detention was "a farcical attack" on freedom of expression.

John Dalhuisen, director for Europe and Central Asia, said: "The absurdity of the case of the Russian blogger jailed for playing Pokémon Go in a church highlights what happens when authorities hold the freedom of expression in such low regard. Even if Sokolovsky's behaviour may have been regarded as disrespectful by some, states should not be jailing people simply for offending religious sensibilities."

Russian Orthodox church leaders believe his actions were offensive but want him released from prison. The local Russian Orthodox Archbishop, Metropolitan Kyrill of Yekaterinburg, said: "We do not crave blood" but wanted to ensure "such actions do not spread". He also wants the video removed.

Pokémon Go itself warns players they should not trespass.

Sokolovsky filmed himself playing the game in All Saints Cathedral in Yekaterinburg built on the site of Ipatiev House where the last Tsar of Russia and the Romanov family were executed in July 1918.

The local city duma chairman Yevgeny Roizman has also appealed for his release and said the blogger's imprisonment was "embarrassing".

Under Russian law, simply catching Pokémon in a church is a crime because it is held to violate the right to freedom of worship.

Sokolovsky said in his video that he did not believe this should be an offence, so he decided to go and hunt Pokémon in a cathedral. He also questioned whether Jesus had ever really existed.

In Russia, some commentators have compared the case to the imprisonment of the Pussy Riot band members after they offended Christians with a performance in Moscow's central cathedral in 2012. It is the tough new "blasphemy" law introduced in 2013 after the Pussy Riot punk group case that is being used now against Sokolovsky.

According to Amnesty, the new law criminalises actions that offend believers' feelings, and is "a further encroachment on freedom of expression in Russia".

Amnesty reports that Sokolovsky deliberately chose to play Pokémon Go in the church on 11 August following a warning made earlier on Russian state television not to catch "Pokémons" at religious sites or in proximity to the state border, or to risk facing criminal charges.