REUTERS/Grigory Dukor Russian President Vladimir Putin speaks during a session of the St. Petersburg International Economic Forum 2015 (SPIEF 2015) in St. Petersburg, Russia, June 19, 2015. 
A "source familiar with the situation" told Interfax on Tuesday that the Russian Prosecutor General's office began checking the legality of the recognition of the independence of the Baltics.
Estonia, Latvia, and Lithuania were Soviet republics until the dissolution of the USSR back in 1991.
The report comes one week after the transfer of Crimea to Ukraine in 1954 - back when Nikita Khrushchev was in power - was declared unconstitutional.
The source stated that the investigation was launched following requests from two parliamentary deputies, adding that there would be no legal consequences if the recognition of the three Baltic states was to be found illegal.
Lithuania's foreign minister Linas Linkevicius called the investigation an "absurd provocation," according to the BBC.
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The report also comes at a time when there's increased tension between Russia and the Baltics.
Over the last year, the Baltic states have been on high alert following the annexation of Crimea and the ongoing conflict in Ukraine. They perceive Russia's increased militarization as a threat to their security interests (and possibly independence.)
Meanwhile, Russia hasn't been happy that Lithuania, Estonia, and Latvia joined NATO back in 2004. And NATO's increased presence in the Baltic states recently hasn't pleased Moscow either.
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