"Kim Clijsters and Lleyton Hewitt have jointly decided to put an end to their relationship for private reasons," Clijsters said on her official website (www.kimclijsters.be).
Clijsters said she and Hewitt did not wish to elaborate on the reason for their split.
"Furthermore, both of us distance ourselves from the malicious gossip which inevitably surfaces in this kind of situation," Clijsters added.
The two tennis players are former world number ones.