Pentagon chief Jim Mattis on Saturday blasted China's actions in the South China Sea, saying Beijing showed "contempt" for other nations' interests. 

"The scope and effect of China's construction activities in the South China Sea differ from those of other countries in several key ways," Mattis told the Shangri-La regional defence summit in Singapore. 

"This includes: the nature of its militarisation... China's disregard for international law ... (and) its contempt for other nations' interests."