British officials said they have uncovered the largest amount of cocaine ever taken in a police seizure from a luxury yacht off the southern coastal town of Southampton.

Officials of the UK Border Agency (UKBA) said they found 1.2 tons of cocaine with a street value of up to £300-million ($492-million) about two months ago.

By comparison, UK police seized a total of 2 tons of cocaine in all of 2010.

"This has been an enormous seizure of cocaine. This is the largest we have on record," said Brodie Clark, head of the UKBA's border force.

The drugs, which were 90 percent pure, were seized from a 65-foot pleasure cruiser, The Louise, which itself is valued at £1-million ($1.6-million).

The coke was so well hidden that it took the police six days to find all of it. The drugs were apparently stored in a specially-designed compartment beneath the boat's bathing platform.

"It was ingenious, it was difficult to find,” Clark commented. "Skillful people spent a number of days looking for it."

The drugs reportedly originated in Venezuela and were on their way to Holland. Dutch police have arrested six men thought to be part of an organized criminal gang in connection with the seizure.

The 60-year-old owner of the boat was arrested in Meppel. His three sons, aged 27, 32 and 34, are also under custody after police conducted raids in Waalwijk and Heusden.

Police also seized 100,000 euros in cash, two Harley-Davidson motorcycles, two firearms, a silencer and the drug ecstasy from the detained suspects.

The vessel had been tracked since May when French authorities were alerted to its presence in the Caribbean.

A Dutch prosecutor, Gert Rip, told media: "About 40 percent of all cocaine brought into Europe is trafficked using smuggling routes from the Caribbean. Venezuela is often used as a supply line of cocaine for the European market."

David Armond, from the Serious Organized Crime Agency (SOCA), said the seizure represented a "great success in the international effort to damage and disrupt the cocaine trade".

Armond added that the amount of drugs seized is "equal to about one-third of the requirement for the UK market over the course of a year.”