Leko represented England at under-16 level. He was ever-present for the under-17s in qualifying for the 2016 European Championships. Against Turkey in the elite round, he set up the first goal for Reiss Nelson and scored the second in a 3–1 win. However, he was unable to take part in the tournament proper because West Bromwich Albion pulled him out of the squad so that he could play in the final two games of the Premier League season.