United Kingdom, Aug. 18 -- Wladimir Klitschko has been left "deeply saddened" by the death of his ex, Hayden Panettiere, aged 36.

The 50-year-old former professional boxer broken his silence on the Heroes and Nashville star's passing, admitting Hayden - who gave him custody of their 11-year-old daughter Kaya - was still an "important part" of his life, despite no longer being his partner.

In a statement on Instagram, he wrote: "Our family is going through a time of profound shock and grief.

"The announcement of Hayden's tragic death saddens me deeply. She left this world far too soon. Hayden was, although no longer my partner, an important part of my life and the mother of our daughter, Kaya."

Wladimir insisted he will "always" speak ...