China’s southern seaboard has replaced the mountainous and tightly guarded western frontier as the preferred route for Islamic extremists to slip recruits out of the country, according to a leading expert on terrorism.

Rohan Gunaratna, the head of the International Centre for Political Violence and Terrorism Research at Singapore’s Nanyang Technological University, claimed that “over 400 Uygurs have left, most through Hong Kong via Indonesia, Malaysia and Thailand to join the IS [Islamic State]”.

He refused to disclose the source of the information about the recruits to the militant group, which is active in Syria and Iraq. “There should be greater intelligence cooperation to detect and disrupt terrorist travel,” Gunaratna told the South China Morning Post.