The main legal question surrounds the USSR State Council in 1991 with the two MPs, Yevgeny Fyodorov and Anton Romanov, saying the council was established illegally and it did not have power to recognize the independence of Estonia, Latvia and Lithuania.

A source working for the prosecution told Interfax a similar decision to the Crimea question is likely to be taken. Russia's chief prosecutor recently ruled that the transfer of Crimea from Russia to Ukraine in 1954 was unconstitutional.

The State Council was set up in the fall of 1991 to oversee the transition of the Soviet Union. The council, which had no Baltic representative, but included the likes of Mikhail Gorbachev and Boris Yeltsin, decided to allow the Baltic states to depart the union in its first sitting. A few months later the council dissolved the Soviet Union.

"It is beyond reason why the Russian state prosecution would waste time and resources on such a legally absurd question," Estonian Foreign Minister Keit Pentus-Rosimannus said.

The council played no part in the legality of Estonian independence from Estonia's own point of view, as Estonian independence was restored, not created in 1991.

It is not the first legal case the two, who are members of President Vladimir Putin's party United Russia, have brought up, attempting to get Gorbachev tried for breaking up the union.