A British passenger on the world's biggest cruise ship has apparently gone overboard in waters near Mexico.

The 30-year-old man was seen falling over the railings by another passenger on the Allure of the Seas, the Royal Caribbean International cruise line said.

He could also be seen falling over in footage from an onboard video camera.

The man went overboard as the ship was sailing to Cozumel, Mexico, and the Mexican navy and coastguard are assisting in the search.

The Allure of the Seas left Fort Lauderdale in Florida on Sunday for a seven-night cruise. The ship can carry 5,400 passengers.

A spokeswoman for the Foreign Office said: "We are aware of the reports and are looking into them."

The guest saw the man fall overboard at 12.10pm (7.10am local time) on Friday, a statement from Royal Caribbean said.

The company added: "The ship made multiple public announcements and began a complete search of the ship, in efforts to locate the guest. When the guest did not respond to the pages and was not found on board, the captain alerted the local authorities of the situation.

"A review of the ship's closed-circuit camera footage observed the 30-year-old British male guest going over the balcony railing in his stateroom on deck 11. The location of the ship at the time the guest went overboard was marked on the ship's Global Positioning System (GPS) and the US and Mexican coastguard were alerted."

A spokeswoman for Royal Caribbean International said the ship had been fully chartered by Atlantis Events, whose website says it is "the largest company in the world dedicated to creating unique vacations for the gay and lesbian community".