LONDON -- British officials said Wednesday they seized 1.2 tons of cocaine in a record-setting drug bust on a pleasure boat.
The U.K. Border Agency and Serious Organized Crime Agency said the cocaine, whose estimated street value is about 300 million pounds ($492 million), was found hidden in a specially-designed compartment on a boat docked in southern England in June.
It was the largest-ever haul of Class A drugs ever found in the U.K., officials said. Britain classifies Class A drugs as those most likely to cause harm.
French authorities alerted British officials to the suspicious craft, Louise, while it was in the Caribbean in May. The boat was traveling to the Netherlands via Southampton, in southern England.
It took six days of searching the vessel to find the drugs because the hiding place was "ingenious," U.K. border agency official Brodie Clark said.
The cocaine, which is believed to have originated in South America and been packed inside the boat in Venezuela, was 90 percent pure, whereas the average purity of cocaine seized at the U.K. border is 63 percent, officials said.
The haul has an estimated wholesale value of 50 million pounds (82 million pounds) and a 300 million pound ($492 million) street value, according to officials. They said the discovery of the drugs in June led to six arrests this week by Dutch police.
Commissioner Gert Ras, of the Dutch National Crime Squad, said the six men arrested were all Dutch nationals and included the 60-year-old owner of the boat and his three sons, aged 27, 32 and 34.
A further arrest of a seventh Dutch national is also expected, he added.