The Customs Union of Russia, Belarus, and Kazakhstan may pull out of its free trade zone with Ukraine if Ukraine signs an agreement on association and establishment of a free trade area with the European Union, Russian presidential adviser Sergei Glazyev has said in an interview with Vesti.

"The issue of ending the free trade relationship with Ukraine may be raised. The Eurasian Economic Commission is already studying this issue," he said. According to him, the customs regime with Ukraine will be tightened in that case.

The adviser to President Vladimir Putin added that customs administration would need to be tightened to avoid re-importation of European goods through Ukrainian territory.

"We will be forced to tighten the veterinary and sanitary control system, since Ukraine is moving to European standards," he said.

Glazyev also said that the programs on cooperation with Ukraine in a number of industries, "including nuclear energy, the military-industrial complex, the aerospace industry, and the aviation industry," might be reduced because Ukraine was assuming "obligations that are too stringent in terms of implementation of European technical regulations and following the European defense and foreign policy."