European safety regulators have sought assurance that Russia is enforcing operating restrictions on carriers, after discovering three airlines were still flying into the European Union despite being banned.
Six airlines operating to the EU had their air operator's certificates modified with restrictions on 2 November.
These carriers included VIM-Avia, Yakutia, Tatarstan Airlines, UTair Cargo, Aviastar-TU and Dagestan Airlines.
However, three operators - VIM-Avia, Yakutia and Tatarstan Airlines - were found to "have actually operated various flights into the EU" after the date of the restriction.
The European air safety committee, which governs the EU blacklist, said it reached this conclusion based on information presented by Eurocontrol.
Another carrier, Aero Rent, also performed commercial flights departing the EU after Russian authority Rosaviatsia decided to revoke its air operator's certificate.
The European Commission said it had been "compelled to request urgent clarifications" from Rosaviatsia and assurances that bans and operating restrictions "were effectively complied with".
VIM-Avia, which uses Boeing 757s, had been subject to a ramp inspection at a French airport which resulted in "numerous significant and serious findings" and led to the aircraft being grounded, said the Commission.
Maintenance approval granted to the carrier by the European Aviation Safety Agency was revoked on 24 May.
Rosaviatsia submitted evidence on 14 November confirming that VIM-Avia's operations had been limited until 1 April 2012, and that services of the other five restricted carriers had been curbed until they had properly addressed safety issues.