The European Union's energy chief said on Wednesday he had reached out to Russia and Ukraine to relaunch EU-mediated talks over their gas dispute and continued gas transits via Ukraine to Europe after their contract expires in 2019.

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"I have reached out to both, Ukrainian and Russian partners, and invited them for trilateral talks," European Commission Vice President Maros Sefcovic said in a statement, according to Reuters.

"The talks... should start as soon as possible in order to take stock of the gas matters important for involved parties and to look into gas transit via Ukraine beyond 2019."

Russian President Vladimir Putin said on Friday that Moscow was ready for talks with Ukraine on continued gas transits through the country, following talks with German Chancellor Angela Merkel.