Ukraine's incumbent President and presidential candidate Petro Poroshenko addresses the media at a polling station during the second round of a presidential election in Kiev, Ukraine April 21, 2019. REUTERS/Vasily Fedosenko

KIEV (Reuters) - Incumbent Ukrainian President Petro Poroshenko on Sunday conceded he had been soundly defeated in a run-off vote by comedian Volodymyr Zelenskiy and would be leaving office next month, but said he did not plan to quit politics altogether.

Ukraine entered uncharted political waters on Sunday after an exit poll showed Zelenskiy, a comedian with no political experience and few detailed policies, had easily won enough votes to become the next president of a country at war.