LONDON (AP) - British police are investigating the theft of 12 "bouncy castles" whose owner claims they were stolen as part of an illicit international trade in inflatable attractions. The bouncy castles - air-filled plastic structures that are common in British fairgrounds and children's parties, and known in the United States as moonwalks - belonged to party organizer Darren Latimer. Latimer, 31, said he believed professional thieves carried out the heist with a view to shipping the stolen goods abroad, and added it was a growing problem in the industry. "It's an up-coming thing to have bouncy castles in places like Spain and South Africa," said Latimer of Bracknell, west of London. "They don't have manufacturers there so it's much more cost-effective to steal them and take them over." Latimer said the stolen equipment, worth the equivalent of about $43,000 Cdn, had been protected by a sophisticated locking equipment, suggesting organized criminals carried out the raid. "It probably would have taken four people to get through that and needed two or three trips in a large van to get them away." He said the bouncy castles were stolen sometime between Feb. 20 and 24. A spokesman for Thames Valley Police, which is investigating the theft and appealing for information, refused to speculate on whether international traffickers were responsible. "It's an ongoing investigation," the spokesman said. "We can't speculate on who did it." He added that he wasn't aware of any other cases of bouncy castle theft. No one was immediately available for comment at the British Inflatable Hirers' Association, a group for people who hire out bouncy castles and inflatable play equipment. A section of the group's website was devoted to postings by members whose equipment has been stolen, but the only message on the site was from Latimer's company Innovents.