More than one million people believed to be held in Xinjiang detainment camps
Detainees are from minorities mostly including Muslim Uyghur people
Allegations of rape, torture and forced sterilisation of female detainees
Refugee Tursunay Ziawudun says she was gang-raped three times
Australian Foreign Minister Marise Payne says reports 'deeply disturbing'
Uyghurs also alleged to work in forced labour camps for major global brands