The measures target the oil, financial and defence sectors of the Russian economy and were first imposed after the shooting down of Malaysia Airlines flight MH17 in July 2014, blamed on pro-Moscow rebels in eastern Ukraine.
Sources told AFP that envoys from the 28 member states of the European Union approved the decision in principle, which will now go to ministers for formal approval, possibly on Friday.
The sanctions were due to expire at the end of July and will now run to January 2017, they said.
Ukrainian President Petro Poroshenko said Tuesday there was no alternative to the EU sanctions to pressure Russia to implement the Minsk ceasefire accords it signed up to.
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"Sanctions are the only instrument left... There is no alternative to that," Poroshenko said, ahead of a meeting with French President Francois Hollande.
The sanctions have been controversial from the start, with EU member states such as Germany, Italy and Hungary fearful of getting locked in a damaging stand-off with Russia, a major political and economic partner.
British Foreign Secretary Philip Hammond warned yesterday it would be "a mistake, a big mistake," to suggest any relaxation of the sanctions regime without real progress on Ukraine.
"The thing that (President Vladimir) Putin understands is clear, decisive postures and a resolute approach on the delivery of the commitments," Hammond said, on the sidelines of an EU foreign ministers' meeting in Luxembourg.
But his French counterpart Jean-Marc Ayrault called Monday in Luxembourg for EU leaders to have a "real debate" on the future of the economic sanctions, which could not just be rolled over automatically every time.
Ayrault's remarks followed comments late last month by German Foreign Minister Frank-Walter Steinmeier that the EU should consider a "step-by-step" relaxation of the economic sanctions if there was progress on Ukraine.
The EU last week rolled over for another year to June 2017 separate sanctions imposed after Russia's March 2014 annexation of Crimea from Ukraine.
The EU has also imposed a separate set of visa ban and asset freeze measures against individual Russian and Ukrainian figures for backing the separatist cause in early 2014. These measures run until September.