In a new report, Amnesty called on China to release all Uighur children detained in orphanages without the consent of their families.
The charity spoke to parents who left their children and relatives in China when they were forced to flee the country.
Rights groups claim that China has seized more than a million Uighurs.
The Chinese government has also faced allegations of various human rights abuses against the people of Uighur and other minority Muslims, including coercion, infertility, sexual harassment and rape.
The government denies arresting Uighurs in camps in Xinjiang province in northwestern China. It says the camps are "re-learning" centers used to fight terrorism.
Because access to Xinjiang was severely restricted by the Chinese, Amnesty spoke to Uighurs who were able to flee Xinjiang before the oppression of the Uighur people increased in 2017.
Mihriban Kader and Ablikim Memtinin fled Xinjiang to Italy in 2016 after being harassed by police and forced to give up their passports, Amnesty said. They left the four children in the care of their grandparents for a while, but the grandmother was taken to the camp when the grandfather was questioned by police, said Sisa.
"Some of our relatives did not have the courage to look after my children after what happened to my parents," Mihriban told Amnesty. "They were afraid they would be sent to the camps as well."
In November 2019, Mihriban and Ablikim obtained permission from the Italian government to bring their children to join them, but the children were caught by Chinese police on the way and sent to a state-run orphanage, Amnesty said.
"Now my children are in the hands of the Chinese government and I am not sure if I will be able to meet them again in my life," Mihriban said.
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Omer and Meryem Faruh, who fled to Turkey in late 2016, left their two children, aged five and six, with their grandparents because they did not have their travel documents, Amnesty said. They later found out that their grandparents had been arrested and sent to a camp where they had never heard of their children.
Amnesty's report calls on China to give Xinjiang full and unlimited access to UN human rights experts, independent researchers and journalists, and all children detained without their parents being allowed to be released into the family.
"China's campaign for mass deportation in Xinjiang has put different families in a precarious position: children are not allowed to leave, but their parents face persecution and unjust imprisonment if they try to return home to take care of themselves," said Alkan Akad, Amnesty International's Chinese researcher.
The Chinese government has created a large and secretive network of camps in Xinjiang and it is estimated that it detained more than a million Uighurs and people from other small Muslim groups.
Reports have surfaced over the years about human rights abuses, ranging from the infertility of Uighur women to organized torture and rape within the camps.
China denies any human rights abuses, and calls in those who have been falsely detained in the camps and deportees. China has also been accused of intimidating and mocking witnesses, and using the relatives of witnesses in Xinjiang as a means of remorse.
The United States, Canada and the Netherlands have announced that China is responsible for the extermination of the Uighur people. A similar bill has been rejected by the UK parliament.