President Vladimir Putin has ordered his government to suspend Russia's free trade zone with Ukraine from January 1, as Kiev seeks closer ties with the European Union.
Russia annexed Ukraine's Crimean peninsula last year and is accused by Kiev of fomenting a bloody conflict with pro-Moscow separatists in the east of the country.
It has staunchly opposed plans to launch an EU-Ukraine free trade pact.
Senior Russian officials said this month Moscow would probably have to penalise Ukrainian imports and impose a non-preferential trade regime if Kiev's planned free trade pact with Europe went ahead on January 1.
Putin's decision to suspend a 2011 free trade treaty with Ukraine was set out in a decree, which cited "extraordinary circumstances affecting the interests and economic security" of Russia.
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The decree on Wednesday made no mention of how long the suspension would last.
There was no immediate reaction from Kiev, where the authorities have previously said there will be no amendments to the free trade agreement with the EU and it will come into force on January 1 regardless of any action by Russia.
Russia says the Ukraine-EU deal could lead to a flood of European imports across its own borders and damage the competitiveness of Russian exports to Ukraine.
