A month later, Haroun was called up to the Belgium U21 squad and made three appearances for U21 side by the end of 2004. He then scored his first Belgium U21 goal, in a 2–1 win against Bosnia and Herzegovina U21 on 25 March 2005. Haroun later scored his second Belgium U21 goal, in a 2–1 win against Lithuania U21 on 11 October 2005. A year later on 6 September 2006 when he scored a brace, in a 2–1 win against Greece U21. It was announced on 12 May 2007 that Haroun was called up to the U21 squad for the UEFA European Under-21 Championship in Netherlands. He appeared four times in the tournament, as Belgium U21 reached the semi–finals.