Hayden Panettiere and her boyfriend Wladimir Klitschko have split up.

The actress and the heavyweight champion boxer have decided to call time on their 18-month romance because they couldn't cope with having a long-distance relationship.

Hayden, 21, lives in the US, while 35-year-old Wladimir - who was raised in the Ukraine - is based in Hamburg, Germany.

A statement from Hayden said: "While we decided to split, we feel great sympathy and respect for each other and will surely stay close friends."

Wladimir added: "We had a great time together. But more and more we realised how difficult it is to maintain a relationship when living on two continents . I cherish Hayden as a person and woman. I'm sure we will stay friends."

Wladimir - whose brother Vitali Klitschko is also a world champion boxer - is currently in training for his heavyweight title unification bout with British fighter David Haye which takes place at the Imtech Arena in Hamburg, Germany, on July 2.