According to police sources quoted by RBK, Antonov was detained as part of an investigation by Russian law-enforcement officials into suspected fraud at Sovetsky Bank. He is suspected of misappropriating the bank's assets.
Latvijas Krajbanka went bust in 2011 after it turned out that huge amounts of money were missing from the bank.
At about the same time, Lithuanian law-enforcement officials launched a pre-trial investigation into suspected misappropriation of Snoras' assets, fraudulent accounting, document forgery and money laundering.
They have brought formal suspicions of abuse of office, misappropriation and squandering of assets, criminal bankruptcy, fraudulent accounting and document forgery against Antonov and Snoras' former CEO Raimondas Baranauskas.
British courts ruled in 2015 to extradite Antonov and Baranauskas, who then lived in London, to Lithuania, but the men fled the UK and are now hiding in Russia.