The European Union scrambled to get a call with Ukraine's president-elect, Volodymyr Zelenskiy, on Monday as Western powers wondered whether the TV comic would heed their urgings to stick with reforms that they hope can anchor the country beyond the grip of Russia.

EU institutional leaders Donald Tusk and Jean-Claude Juncker wrote jointly to congratulate the 41-year-old political novice on an easy win over Petro Poroshenko, for five years the West's champion in Kiev. But they also stressed that they are counting on more democratic reforms and fighting corruption.

Highlighting Sunday's smoothly run vote as a "major achievement" after five years in which the EU has pumped cash into Ukraine and borne the cost of economic sanctions on Moscow, the respective presidents of the European Council and Commission urged Zelenskiy to seek continuity.