Authorities were searching Thursday for two passengers who were believed to have gone overboard while traveling on a cruise ship off the east coast of Australia.

The couple, a 30-year-old man and 26-year-old woman traveling with family and friends, were discovered missing when the Carnival Spirit docked in Sydney after a 10-night cruise, according to a statement from Carnival Cruise Lines.

Police said footage from the ship’s surveillance cameras showed that the couple, who are from the Australian state of New South Wales, went overboard from the ship’s mid-deck Wednesday night, according to the Associated Press.

It was not immediately clear whether they had fallen or jumped. The statement from Carnival Cruise Lines said there was no evidence of foul play, but the company would not disclose details of what happened, out of respect for the families.

Search boats and aircraft were combing the area where the couple were believed to have gone missing.

“This is a tragic event at the moment, but we're holding out hope we might be able to find these people alive,” New South Wales Police Supt. Mark Hutchings was quoted as saying by the  AP.

It was the latest in a series of high-profile problems for Miami-based Carnival Corp., the parent company of Carnival Cruise Lines.

Last year, the Costa Concordia cruise ship ran aground in Italy, killing 32 people.

A sister ship, the Costa Allegra, lost power in the Indian Ocean after a fire broke out in the engine room last year, leaving passengers without working toilets or air conditioning for three days. 

In February, the Carnival Triumph lost power during a cruise out of Galveston, Texas, and had to be towed out of the Gulf of Mexico to Mobile, Ala.

“We have naturally been concerned since we became aware that two passengers were missing from Carnival Spirit and our thoughts are clearly with their families at this difficult time,” Carnival Cruise Lines said in Thursday’s statement. “We are working closely with New South Wales Police and assisting them in their inquiries.”

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Twitter: @alexzavis

alexandra.zavis@latimes.com