China suspended high-level exchanges with Japan on Sunday and promised tough countermeasures after a Japanese court extended the detention of a Chinese trawler captain who collided with two Japanese coastguard ships, Reuters reported. "China demands that Japan immediately release the captain without any preconditions," Foreign Ministry spokesman Ma Zhaoxu said in a statement on the ministry's website, repeating that China viewed the detention as illegal and invalid. "If Japan acts wilfully despite advice to the contrary and insists on making one mistake after another, the Chinese side will take strong countermeasures, and all the consequences should be born by the Japanese side," Ma said.