HONG KONG >> Chinese officials have detained relatives of at least four reporters who covered an extensive crackdown in the Xinjiang region for Radio Free Asia, the U.S.-based broadcaster has said, raising questions about an intimidation and retaliation campaign.

The four journalists all work for the broadcaster’s Uighur service, which has been aggressively covering the situation in the nominally autonomous region of Xinjiang, Radio Free Asia said Wednesday.

Since 2017, the Chinese government has carried out a broad campaign against what it calls separatism and religious extremism, detaining thousands of Uighurs and members of other minority groups in re-education camps. The Uighurs, a predominantly Muslim and Turkic-speaking ethnic group native to the region, have faced economic isolation and restrictions on their language, culture and religious practices in Xinjiang.

Rights groups say the detentions are arbitrary and extralegal, sweeping up huge numbers of people on scant evidence.

Some attacks on security services and civilians in China have been linked to people calling for an independent Uighur state. But the breadth of the crackdown appears intended to punish dissent and intimidate any Uighurs who might question Chinese policy, rather than just to curb violence, rights groups say.

Uighur-speaking journalists for Radio Free Asia, which is based in Washington, have documented grim conditions in the camps and deaths in custody. Officials at the network questioned whether the detentions of journalists’ family members were ordered in retaliation for their reporting.

“Harassment is nothing new for RFA’s journalists, especially among our Uighur and Tibetan staff with family in China,” said Rohit Mahajan, Radio Free Asia’s director of public affairs.

But the latest detentions are much more extensive than previous ones, he said.

“Often, our reporters have family members called in for questioning or detained,” Mahajan said. “They don’t want attention because they think it possible their relatives will simply go through the system.”

He added, “That’s obviously not the case with these individuals.”

The reporters whose relatives were detained are Shohret Hoshur, Gulchehra Hoja, Mamatjan Juma and Kurban Niyaz, Radio Free Asia said. Niyaz is a permanent resident of the United States with a green card, while the three others are U.S. citizens.

Some of the family members are being held in detention camps, some have been sentenced to prison, some are being held in jails and the whereabouts of others are unknown, Mahajan said.

Their detentions were first reported by The Washington Post.

The Chinese government keeps tight control over information about Xinjiang, the far western part of the country, and reporting in the region can be extremely difficult. Hoshur worked as a reporter there before fleeing in 1994, after he reported two stories that angered officials. He is now based in Washington, where he learns details about little-known episodes in Xinjiang by calling police stations and demanding answers from local officers.

In 2014, his three brothers were arrested, apparently in retaliation for his reporting. One brother, Tudaxun Hoshur, is serving a five-year sentence for endangering state security. Rexim Hoshur and Shawket Hoshur, who were released in 2015, were detained again in September and are being held at a re-education camp.

Hoshur has said he would not quit, despite the pressure, because so many people had taken great risks to pass along information from Xinjiang. “I cannot leave,” he told The New York Times in a 2015 interview at Radio Free Asia headquarters in Washington.

Hoja said in a statement posted online that her brother Kaisar Keyum, 43, had been detained in October, and that she had not been able to reach her parents, who are in their 70s, since late January.

A relative of Hoja’s in West Virginia told her that she had been warned against staying in contact with her. “I am the reason that around 20 of my relatives were arrested by the Chinese police,” she wrote.

Juma said his brothers Ahmetjan Juma and Abduqadir Juma had been detained in May. Abduqadir, who has heart and other health problems that require medical care, is being held at Urumqi No. 1 Prison in the capital of Xinjiang. Ahmetjan’s location is unknown.

Niyaz’s youngest brother, Hasanjan Niyaz, was accused of “holding ethnic hatred” and arrested in May. He was sentenced in July to six years in prison.

Human Rights Watch reported this week that Chinese officials were using data analysis to try to identify people in Xinjiang who might be viewed as threatening. The system uses data on banking, family planning, health and legal records, as well as networks of sensors and cameras with facial recognition technology to generate lists of people of interest to the authorities, the rights group said.

© 2018 The New York Times Company