The International Criminal Court has decided not to pursue an investigation into China’s mass detention of Muslims, a setback for activists eager to hold Beijing accountable for persecution of ethnic and religious minorities.

Prosecutors in The Hague said on Monday that they would not, for the moment, investigate allegations that China had committed genocide and crimes against humanity regarding the Uighurs, a predominantly Muslim ethnic group, because the alleged crimes took place in China, which is not a party to the court.