AceShowbiz -

Nicole Kidman is mourning the sudden death of her father Dr. Antony Kidman. The highly-respected Sidney-based clinical psychologist collapsed in a Singapore hotel room while visiting his younger daughter Antonia and her family in the country.

According Daily Mail Australia, the Kidman patriarch was pronounced dead at the Tan Tock Seng Hospital. Police said Friday, September 12 that they were investigating the "unnatural death," a term which, in Singapore, often refers to falls or other accidents.

Nicole hasn't issued a statement, but a publicist for the "Grace of Monaco" star says "the family is in shock and is grieving." In the wake of the sad news, Keith Urban canceled his scheduled performance at a charity event at Sherwood Country Club in Thousand Oaks, CA to be by his mourning wife's side at their home in Nashville.

Antony and wife Janelle Kidman celebrated the 50th anniversary of their wedding in January this year with their family including Nicole and her country singer husband. "We were a close-knit family - still are," the actress told DuJour magazine last year.

"It is with great sadness that we learn of Dr Tony Kidman's sudden passing. During his 43 years at the University of Technology, Sydney, Tony has contributed greatly - as a colleague, as a researcher, and as a health practitioner," said Vice-Chancellor Professor Attila Brungs to Reuters. "Tony will be missed by all at UTS. Our thoughts are with his family at this time."