The Customs Union of Russia, Belarus and Kazakhstan will be forced to step up customs procedures for Ukraine and may withdraw from a free trade area with the country if Kyiv signs an agreement on association and free trade area with the EU, Russian presidential advisor Sergei Glazyev has said.

"The matter of ending the free trade relations with Ukraine may be raised, the Eurasian Economic Commission is already studying this issue," Glazyev said in an interview with the Vesti newspaper.

According to him, the union will need to tighten customs procedures to avoid the re-importing of European goods through Ukraine.

"We will have to tighten the system of veterinary and sanitary control, due to Ukraine switching to European standards," the Russian president's adviser said.

"Many projects that we have planned together with Ukrainian partners, including in nuclear energy, the defense industry, the rocket and space industry, and the aviation industry will be reviewed in terms of reducing them, as Ukraine is taking on too strict obligations in complying with European technical regulations and European defense and foreign policy," Glazyev said.