On February 9, Russia's lower house of parliament passed a bill granting the authorities in the republic special rights based on its high concentration of mostly Muslim ethnic Tatars.
"I still believe it is dangerous to endorse this agreement," Sergei Mironov said. "Federalism must remain a major principle for all subjects of the Russian Federation."
The agreement stipulates that the federal government and Tatarstan's Cabinet negotiate a deal allowing Tatar authorities to have a greater say in decisions involving economic, environmental, cultural and other regional issues.
The document also guarantees that a leader of Tatarstan, whose candidacy is proposed by the Russian president, must speak the Tatar language in addition to Russian.
The republic will also have the right to issue internal identification papers with an insert in Tatar.
Mironov, who warned in last December that the power separation agreement with Tatarstan could encourage separatist sentiments in other regions, said the Federation Council is split on the issue, and that the results of the upcoming debate in the upper house are unpredictable.
Fears that the oil-rich region on the Volga River could secede from Russia have been a major concern for federal authorities ever since the collapse of the Soviet Union and Chechnya's drive for independence in the 1990s that led to a prolonged and devastating conflict.
