BEIJING, Dec 26 (Reuters) - China has replaced Chen Quanguo, who as Communist Party chief in the Xinjiang region oversaw a security crackdown targeting ethnic Uyghurs and other Muslims in the name of fighting religious extremism. Chen, in his post since 2016, will move to another role and Ma Xingrui, governor of the coastal economic powerhouse Guangdong province since 2017, has replaced him, the official Xinhua News Agency said on Saturday. It gave no other details. United Nations researchers and human rights activists estimate more than one million Muslims have been detained in camps in western China"s Xinjiang region. China rejects accusations of abuse, describing the camps as vocational centres designed to combat extremism, and in late 2019 said all people in the camps had "graduated". Chen, 66, is a member of China"s politburo and is widely considered to be the senior official responsible for the security crackdown in Xinjiang. He was sanctioned last year by the United States. On Thursday, U.S. President Joe Biden signed into law a ban on imports from Xinjiang over concerns about forced labour, provoking an angry Chinese condemnation. read more Some foreign lawmakers and parliaments, as well as the U.S. secretaries of state in both the Biden and Trump administrations, have labelled the treatment of Uyghurs genocide.