"There are credible reports out there that many, many thousands have been detained in detention centers since April 2017, and the numbers are fairly significant from what we can tell so far", Nauert said.
The State Department on Tuesday expressed concern following reports of mass detentions of ethnic Uighurs and other Muslims, which has prompted worldwide outcry.
Citing unnamed current and former officials, the Times reported the administration has been discussing sanctions over the human rights issue for months at the White House, Treasury Department, and State Department.
Chinese Foreign Ministry Spokesman Geng Shuang said Monday the measures in Xinjiang were necessary to "crack down on ethnic separatist activities and (violence) and terrorist crimes".
In August, a bipartisan group of USA lawmakers called for Chinese officials involved in alleged human rights violations in Xinjiang to be sanctioned under the Global Magnitsky Act - the 2012 law originally created to freeze the assets of certain Russian government officials and businessmen accused of human rights violations.
"The Chinese government protects people's freedom of religion and people of all ethnic groups are fully entitled to freedom of religion". Although Beijing has denied the allegations, Xinjiang authorities have acknowledged the existence of "political education camps" and "characterize them as correctional or rehabilitation facilities for "incorrect" or "sick" thoughts", HRW writes.
The rights watchdog said that 1 million people are being held in detention camps, where Turkic Muslims are being forced to learn Mandarin Chinese, sing praises of the Chinese Communist Party, and memorize rules applicable primarily to Turkic Muslims.
Michelle Bachelet, the High Commissioner for Human Rights decried the treatment dished out to the Uighur community in China during her first remarks as head of the United Nations rights watchdog in Geneva, Switzerland.
The US followed a report by UN Human Rights panel that China has detained over a million Uygur Muslims in re-education camps also called indoctrination camps.
QR codes are now being installed on the homes of Uighur Muslims in the Xinjiang region in northwest China, according to a Human Rights Watch report released on Sunday.
This would be one of the first times the administration would take action against China economically for mistreating Chinese Muslims.
As many as 13 million Muslims living in the region are increasingly subjected to mass arbitrary detention, torture and mistreatment by the Chinese government, the report noted.