MOSCOW, December 15 (RIA Novosti) – An environmental activist who often targeted Russian officials, including President Vladimir Putin over the infamous “Putin’s Palace,” said on Saturday that he was placed on a federal wanted list.

Suren Gazaryan is wanted over accusations that he threatened to kill a security guard protecting the “Putin’s Palace,” he wrote on Twitter.

Police in the southern city of Gelendzhik, which handles the case, made no official statement as of Saturday night. The Kremlin also issued no comment.

Death threats are punishable with jail terms of up to two years in Russia.

Gazaryan has previously criticized the presidential administration over the posh mansion it built outside Gelendzhik in Krasnodar Region, saying that it was erected with environmental violations. The mansion, which he claimed came with a price tag of $1 billion, was dubbed “Putin’s Palace” by the media.

The Kremlin denied the accusations, while a security guard at the mansion said in August that Gazaryan threatened him and threw stones at him.

Gazaryan, 38, a member of the Yabloko party who sits on the opposition’s Coordination Council, made a name for himself by campaigning against environmental violations on Russia’s southern Black Sea coast, a lucrative piece of real estate that attracts many developers.

Gazaryan has campaigned against a port terminal in the local city of Tuapse set to handle dangerous chemicals, criticized construction projects for the 2014 Sochi Olympics and accused Krasnodar Governor Alexander Tkachev of building a country house on land that was allegedly state-owned. Tkachev dismissed the allegations.