if issued in Non-Russian Currency wthere are certain requirements beside an approval code from the Central Bank and a non Russian payment agent. Marketability of a VTB BG is relatively low because the possibility to interfere under the Russian jurisdiction and in the current climate this type of risk is just a non no. VTBobviously needs money and does not want to tab its already streched credit facilities, so they will not have a foreign confirmation.
Their rating see : http://www.vtb.com/rus/web.html?s1=2270&l=2
Just think again: This bank has just placed 1B Euro's in Bonds, has its own Investment Nanking Department and certainly does not need any gray market brokerage, especially when such pricing and procedure would cause raised eyebrows.
I suggest you get the details and ask them direct if it is real.