Russian Prime Minister Vladimir Putin said Tuesday that Ukraine and other ex-Soviet republics making up the Commonwealth of Independent State have agreed to set up a free trade zone.
"After long, tense but ultimately constructive negotiations, we resolved the main issue," Putin said during talks with his CIS counterparts in Russia's second city of Saint Petersburg.
"We have agreed to sign today an agreement on a free trade zone in the CIS," Putin said moments before the signature ceremony.
His comments came just hours after Ukraine suffered a blow to its hopes of establishing free trade relations with the European Union when Brussels postponed a key summit over the jailing of opposition leader Yulia Tymoshenko.
The 11-nation bloc was formed in an urgent bid to give some structure to the struggling but interdependent republics that made up the Soviet Union prior to its collapse in 1991.
The union always excluded the three Baltic republics -- tiny lands that saw Soviet forces who made them a part of the USSR during World War II as occupiers -- and later lost Georgia after its 2008 war with Russia.
Ukraine is one of the founding members but has also had difficult ties with group. It never formally ratified the bloc's founding documents and is now seeking closer relations with the EU and its 500-million-strong market.
But Russia has been hoping to make the various post-Soviet unions more effective as it tries to reassert its control over the land.
Putin also spoke of a "Eurasian" economic union in a rare article he published this month.
Thursday's summit in Brussels was meant to give Ukrainian President Viktor Yanukovych the chance to put the finishing touches on an association agreement that marks the first step to full EU membership.
Yanukovych has previously resisted Russia's calls to join a separate economic union led by Russia that also includes Belarus and Kazakhstan.
Putin was due to hold separate talks with his Ukrainian counterpart Mykola Azarov after the prime ministers completed signing a raft of 28 documents that included the free trade zone deal.
The Russian premier called the economic deal "a fundamental agreement that will lie at the foundation of our economic and trade relations."