BRUSSELS -- A leaked letter from German Foreign Minister Frank-Walter Steinmeier urges the European Union to quickly ease "Russian concerns" regarding the implementation of a free-trade agreement with Ukraine.

In the letter addressed to European Commission President Jean-Claude Juncker, which was made available to RFE/RL, Steinmeier called for a resumption of three-way talks between the EU, Ukraine, and Russia in order to identify "practical solutions."

Russia has voiced opposition to the creation of a Deep and Comprehensive Free Trade Area (DCFTA), the economic core of a wide-ranging Association Agreement concluded in March 2014 by the European Union and Ukraine.

Critics in Russia say the deal would have a negative impact on the Russian economy.

Russian President Vladimir Putin has warned Ukraine that changing national legislation to prepare for the agreement would trigger "an immediate response from Moscow."

Ukraine, in turn, argues that Russia is not a party to the Association Agreement and has no right to interfere.

After being postponed amid Russian resistance, the DCFTA is due to enter force by January 1, 2016.

In the letter, dated April 2, Steinmeier urged the European Commission to "use the considerable flexibility that the agreement offers."

He said Germany strongly supported the swift implementation of the DFCTA, adding that "time is running short."

He added that "the economic stability of Ukraine can hardly succeed without the participation of Russia" and called for a "pragmatic, interest-based and political approach without preconditions."

The protests in Kyiv that led to the ouster of Ukraine's pro-Russian President Viktor Yanukovych in February 2014 were sparked by his abrupt to decision to shelve plans to sign an Association Agreement with the EU and bolster trade ties with Moscow instead.

Russia's annexation of Crimea in March 2014 and its support for separatists fighting government forces in eastern Ukraine have further strained Moscow's relations with Ukraine and the European Union.