Kidman's father in hospital

Nicole Kidman's father has undergone heart surgery in Australia, according to reports.

The actress' sister Antonia revealed the news on Monday at a TV prizegiving in Sydney.

Collecting the ASTRA Award for Favourite Female Personality, Antonia held back tears as she accepted the honour onstage at the Hordern Pavilion.

She said: "It is a sweet end to a sad day because my dad's in hospital."

She refused to reveal more, but reports suggest the Kidman patriarch, a renowned psychologist, underwent scheduled heart surgery hours before his daughter collected her TV award.