MOSCOW, Dec. 28 - Ukraine's accession to the Customs Union of Russia, Belarus and Kazakhstan is vital for all members of the association, presidential advisor Sergei Glazyev said at a Thursday session of the Duma Committee for CIS Affairs.

"Ukraine's accession to the Customs Union would be very important for all members and vitally necessary for Ukraine itself. All our calculations prove that," Glazyev said.

"Without joining the Customs Union, Ukraine will be unable to balance either its trade balance or the balance of payments," Glazyev said.