The European Commission's president will meet with Russian President Vladimir Putin next week.

Jean-Claude Juncker will be the most high-profile EU official to go to Russia since it annexed the Crimean Peninsula from Ukraine in 2014. He will address a Russian economic conference in St. Petersburg on Thursday and his office said he would also meet with Putin, who is attending the conference.

Both sides have already warned against any optimism of a sudden warming in relations and Juncker said last week there would be no letup of sanctions against Russia.

Like the U.S., the 28-nation EU has effectively frozen ties with Russia and imposed sanctions following the 2014 seizure of Crimea.