Hassan became a Dutch citizen in November 2013 and the following month she made her first appearance for the Netherlands. At the 2013 European Cross Country Championships she won the gold medal in the under-23 category and helped the Dutch team to third in the rankings. She also won the Warandeloop and Lotto Cross Cup Brussels races that winter. At the beginning of 2014 she ran a world leading time of 8:45.32 minutes for the 3000 m at the Weltklasse in Karlsruhe, then broke the Dutch record in the indoor 1500 m with a time of 4:05.34 minutes at the Birmingham Indoor Grand Prix.