Shanghai | A mobile app is being used to carry out illegal mass surveillance and detention of Muslims in western China's Xinjiang region, according to a new report linking some of China's technology giants such as Alibaba to what the United States has called a violation of human rights.

The report by New York-based Human Rights Watch (HRW) details a sophisticated surveillance system known as the Joint Operations Platform (IJOP), which officials use to monitor the behaviour, movements and spending patterns of 13 million Uighur Muslims.