Drug traffickers are targeting cruise liners to smuggle cocaine from the Caribbean and South America to Europe, the Serious Organised Crime Agency and the UK Border Agency have warned.
They claim there is growing evidence criminals are placing drug couriers on board and attempting to corrupt crew.
Staff and travel agents have been given a list of tell-tale signs, they added.
The warning comes as four Bulgarians and four Lithuanians are due to be sentenced at Canterbury Crown Court.
UKBA officers found 35kg of cocaine sewn into body suits in cabins occupied by those being sentenced when they searched the MSC Orchestra - which had docked at Dover en-route to Amsterdam from Brazil - on 6 May 2010.
Soca and the UKBA said couriers placed on board by organised criminals have the potential to "smuggle multi-kilo loads of cocaine or heroin".
Soca executive director Brad Jones said: "Organised crime groups will always attempt to take advantage of legitimate business for their own ends, so Soca works closely with industry to restrict the opportunities available to them.
"By warning the cruise and travel industries of potential signs of criminal exploitation, we can stop ships from being an attractive form of ready-made transportation for drug traffickers ."
Cruises have become increasingly popular with UK holiday makers over recent years, now accounting for one-in-10 package holidays.
Advice offered to the industry includes paying close attention to passengers who book last minute and pay in cash.
Those that choose not to engage in on-board activity, or do not appear to fit in with the other passengers - such as younger passengers on a cruise targeted at the over-50s - should also be scrutinised, they said.
They have have also advised staff to be on the look out for crew who attempt to access areas of the ship not associated with their job.
In May 2010, two unemployed Spanish men were jailed for 12 years each following a failed attempt to smuggle 33kg of cocaine through Southampton.
Tanasu De Jesus Quevedo-Ojeda, 28, and Oliver Vidal Hernandez, 27, had boarded the Black Watch cruise liner in Peru and were due to remain with the ship as it travelled to the Canary Islands via Southampton.
They were arrested as they disembarked the ship at Southampton on 27 March.
The cocaine was concealed inside leggings worn beneath their trousers and they had been paid to deliver to the UK, Gran Canaria and Tenerife.
7 January 2011 Last updated at 03:28 GMT
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