China's shipping industry has lobbied against such ships, fearing they may strengthen Vale's dominance on the dry-bulk market and China's Ministry of Transport has restricted their access to its ports.
Home Secretary David Blunkett and Transport Secretary Stephen Byers have demanded an urgent report into how robbers accessed the restricted zone amid heightened security since 11 September.
"They're more restricted when you get into adverse weather, " says David Castelveter, a spokesman for the Air Transport Association, the industry group for major carriers.