The main sanctions, which target Russia's energy, defense and financial sectors, would otherwise be due to expire at the end of January 2018, Reuters said

Read alsoRussia fails to create power grids operator in occupied Crimea – mediaEU leaders meeting in Brussels on Thursday will agree an extension until mid-2018, officials and diplomats in Brussels said.

Moscow says it will never return Crimea, which it annexed in 2014 in a move that has not been recognized internationally. Western countries say Russia has also been providing a lifeline to separatists in eastern Ukraine, where a conflict has killed more than 10,000 people since 2014.