NAIROBI, Oct 2 - Piracy in the Gulf of Aden has cost shippers between $18m-$30m so far this year in ransoms and is threatening global business, British think-tank Chatham House said on Thursday.

Pirates have hijacked more than 30 ships off Somalia this year, making the country’s 3,300 km (2,060 mile) coastline one of the most dangerous in the world and threatening an important shipping lane between Europe and Asia.