A British national has been charged after allegedly assaulting a fellow passenger on a cruise ship earlier this week.

After embarking and setting sail on the cruise ship from Sydney, the man, 71, allegedly attacked another passenger on Wednesday while the ship was at sea.

The crew turned the ship around and the man was charged by police when they returned to port in Sydney on Saturday.

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Detective acting Superintendent Trevor Robinson said safety on board international vessels was paramount.

“The repercussions of alleged criminal behaviour remain even when an offence occurs at sea,” he said.

“Where Australian law applies under the Crimes at Sea framework, the AFP will move swiftly to investigate incidents and bring alleged offenders before the courts.

“We work closely with cruise operators and maritime partners to ensure the safety of passengers and crew, and to make it clear unlawful behaviour on vessels connected to Australia will be addressed.”

The man was arrested and charged with one count of assault occasioning bodily harm.

He is scheduled to appear at Downing Centre Local Court on February 18.