An air and marine search is underway off the Australian east coast for two passengers who were discovered missing after a cruise ship docked in Sydney Harbor.

Police Sgt. David Rose says the man and woman were discovered missing after the Carnival Spirit docked at Sydney's Circular Quay Thursday morning.

He says a marine and air search is underway but gave no further details.

Australian Associated Press reports the search for the 30-year-old man and 26-year-old woman extends from Sydney 100 kilometers (60 miles) north to the city of Newcastle. Their nationalities have not been released.

A spokeswoman for ship operator Carnival Corp. was not immediately available for comment.

The Miami-based company is the world's largest cruise operator and has been plagued by high-profile problems in recent years.