Beijing (AFP) - China's all-encompassing security crackdown in Xinjiang has turned the northwest region -- home to most of the country's ethnic Uighur population -- into a place activists describe as an open air prison.

Upwards of one million mostly Muslim ethnic minorities in the region are held in re-education camps, according to estimates cited by a UN panel in 2018.

And for those living outside the camps, ubiquitous ID checks and tight security are a part of daily life.

The United States blacklisted 28 Chinese entities this week over their alleged roles in rights violations in Xinjiang and said it would also curb visas for officials involved in "detention or abuse" of minorities.

Here are some key parts of China's Xinjiang security apparatus:

- Re-education camps -

The most controversial aspect of China's security crackdown in Xinjiang is its vast network of re-education camps, where rights groups and former inmates say detainees are subject to forced political indoctrination and even abuse.

A Kazakh businessman, who spent nearly two months in a camp, told AFP the facilities only had one goal: to strip detainees of their religious belief.

Inmates were forced to sing patriotic songs every morning and eat pork, a violation Islam's religious restrictions, he said.

An AFP investigation of over 1,500 government documents last year also found that Xinjiang camps were run more like jails than schools as claimed by Beijing.

Tasers, tear gas, and even "tiger chairs" -- used by Chinese police to restrain interrogation subjects -- were among items requested by centres around Xinjiang.

Still, the Chinese government has defended what it calls "vocational education centres" as a necessary countermeasure for religious extremism, despite denying their existence until last October.

- High-tech surveillance -

Outside of the camps, local residents in Xinjiang are tightly monitored by an array of high-tech surveillance systems.

A mobile app called the Integrated Joint Operations Platform collects information from multiple sources, including facial-recognition cameras, wifi sniffers, and home visits in the region, according to Human Rights Watch.

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Xinjiang authorities use the app to target specific individuals, such as those who donate to mosques "enthusiastically", do not socialise with neighbours, and do not use a smartphone, the group found.

In April, a report by the New York Times also revealed that Chinese authorities are using a vast system of facial recognition to track Uighurs across the country.

In the central Chinese city of Sanmenxia, Chinese authorities scanned whether residents were Uighurs 500,000 times in one month alone, according to the newspaper.

Data leaks have also offered clues to the scale of surveillance across all ethnic groups.

Within a 24-hour period, more than six million locations were saved by tracking devices in Xinjiang, according to a Dutch security researcher who discovered an exposed database in February.

The database also stored a range of personal information on 2.6 million people in the region, including ethnicity, address, and employer.

- Religious restrictions -

In 2017, Xinjiang authorities passed sweeping "anti-extremism" regulations that banned a wide range of behaviours and customs -- formalising a regional crackdown on certain Muslim practises.

Growing "abnormal" facial hair was included in the government's list, as well as wearing robes that cover the whole body and face.

The new regulations also required Uighurs to watch or listen to government propaganda on radio or TV.

A visit to Xinjiang during the month of Ramadan by AFP journalists also showed profound changes in Uighur-dominant cities like Kashgar, where a sunrise prayer call used to echo throughout the city.

This year, the celebration of Eid al-Fitr was a quiet affair, with locals filing into the city's state-approved mosque as police and officials fenced off the surrounding area.

Since 2017, dozens of mosques and religious sites around Xinjiang have also been demolished or stripped of their domes, according to satellite images analysed by AFP and Earthrise Alliance.

A new AFP investigation found that at least 40 cemeteries were destroyed in the region.

- Controls overseas -

Beijing's push to control the Uighur population has also extended well beyond Chinese borders.

In July 2017, Egyptian authorities aided Chinese officials in a police raid targeting Uighurs in the country.

One Uighur, who was an Islamic theology student in Egypt at the time, told AFP he was taken to a Cairo police station where Chinese officials grilled him about his life in Egypt.

Then he was sent to Tora, one of Egypt's most notorious jails, and detained for 60 days.

Uighurs in countries as far away as the United States have also told AFP they have received menacing messages and explicit threats to relatives in Xinjiang -- part of China's powerful state security apparatus's bid to silence activists and recruit informants.

One man told AFP he remains reluctant to speak publicly despite now being a New Zealand citizen because he fears for himself and his 78-year-old mother.

After Shawudun Abdughupur refused to give details of his meetings with other Uighurs, he received this chilling message: "We can find you. We are in New Zealand."