When Bacha Khan, a Pakistani trader, returned from a trip abroad to his home in China’s northwest this spring, his Chinese wife and three of his children had disappeared and their house had been demolished.
Police told him his family had been taken into custody, he said, adding to the up to 1 million people, most of them Muslim ethnic Uighurs, that the United Nations estimates have been detained by China in camps in its Xinjiang region.
Mr. Khan and dozens of other Pakistanis whose Uighur wives are in the camps have lobbied Pakistani authorities for help for months. Last week, they got a boost when a minister in Pakistan’s new government spoke out for the first time about China’s policies in Xinjiang.
It was a rare indication of official concern about the issue within the Islamic world, and added to a growing backlash among Muslims world-wide that presents a thornier challenge for Beijing than Western government censure.
Muslim groups in India and Bangladesh held protests over the Chinese camps for the first time this month after former inmates began to talk publicly about their treatment, including being bound to chairs for hours on end and forced to renounce Islamic beliefs.
In Kazakhstan, many people were also outraged, and local lawyers and activists say hundreds of people have lobbied their government for help, following the detention of several Kazakh citizens and many more ethnic Kazakh Chinese nationals in the camps.
Hizb ut-Tahrir, an Islamist group that claims a million members in 40 countries, called on Muslims this month to be wary of Chinese investment and to oppose Chinese rule in Xinjiang.
On Saturday, the group accused Pakistan’s government of betraying the Uighurs for the sake of China’s infrastructure program in the country, known as the China-Pakistan Economic Corridor, or CPEC.
“Should the Muslims of Pakistan quietly observe the persecution of Uighur Muslims for the sake of CPEC and China?” it asked.
China began the mass detentions about two years ago as part of a drive to snuff out an occasionally violent Uighur separatist movement that Beijing says has links to foreign jihadists. Some Uighurs have joined Islamic State in Iraq and Syria.
However, rights groups and Uighur activists abroad say unrest in Xinjiang is driven mainly by heavy-handed policing, tight restrictions on religious activities and one of the world’s most intensive electronic surveillance systems.
The U.S. has strongly criticized the detention camps and some European countries are reviewing immigration and asylum policies. Sweden this month joined Germany in suspending deportations of Uighurs to China.
The backlash in the Islamic world is more troubling for China as it could rally international support for the Uighurs and foment opposition to its “Belt and Road” infrastructure building initiative.
Concerns about the restrictions on Muslims in Xinjiang were raised by Pakistan’s religious affairs minister, Noorul Haq Qadri, in a meeting with China’s ambassador to Islamabad on Sept. 19, according to a person familiar with the matter.
After Pakistani media reported Mr. Qadri’s message, the Chinese Embassy issued a statement to assert that the reports were incorrect, and that the two men had reached consensus on promoting religious harmony. Xinjiang, it said, enjoys harmonious coexistence among ethnic groups.
Chinese officials say the camps are vocational training centers for minor criminals and deny that a million people have been detained, without providing their own estimate of the numbers.
Governments in the Islamic world have been reluctant to criticize China, fearing they could lose out on “Belt and Road” funding, according to diplomats and foreign-policy experts. Those governments have also often put pressure on local clerics and media not to discuss the camps, the diplomats and experts said.
“They’re scared. Nobody wants to say anything,” Anwar Ibrahim, who is in line to become Malaysia’s next premier, said in an interview with Bloomberg Television this month when asked why Muslim countries had been largely silent on the Uighur issue.
Pakistan has been the biggest recipient of Chinese infrastructure loans; its last government, whose term ended in May, made no public statement about China’s policies in Xinjiang, which borders Pakistan, India and several other countries.
The new government in Islamabad, under Prime Minister Imran Khan, is pressing China to revise the goals of its $62 billion infrastructure program in Pakistan and working with Beijing to shrink Pakistan’s trade deficit, goals that could be complicated by complaints about one of China’s most sensitive national-security issues.
“Before Pakistan government and China government, they no care about this. But this government now Imran Khan, they start help,” said Shahid Ilyas Hussain, a Pakistani man whose wife has been detained.
Mr. Hussain said he hasn’t been able to contact her since she was taken from their home in Xinjiang’s capital, Urumqi, while he was away in Beijing in April 2017.
He and others involved in lobbying Pakistan’s government said there were more than 300 Pakistani men whose Chinese wives had been detained in the camps, many of whom were now seeking Chinese or Pakistani passports for their spouses so they could leave China.
Mr. Khan, the trader, said local police wouldn’t allow him to see his family and demanded 100,000 yuan ($14,500) per child to have them released.
“If my wife has broken the law, then go through the legal process for her,” he said, speaking from Urumqi. “But what crime have my children committed? They are so young and innocent.”
Two Pakistani traders, Mirza Imran Baig and Asif Mohammad, said they met Pakistan’s ambassador in Beijing on Tuesday to seek help obtaining Chinese passports for their Uighur wives.
A Pakistan Embassy official in Beijing said several Pakistani citizens had filed applications for assistance for their detained wives, which he said had been forwarded to Islamabad. He declined to provide further details and Pakistan’s foreign ministry didn’t respond to requests for comment.
A Chinese foreign ministry spokesman didn’t respond directly to a question at a news briefing Tuesday about Pakistani nationals whose Chinese wives have been detained.
Pakistan’s Islamic clerics and organizations, which often protest over rights abuses against Muslims in other countries, have mostly remained silent on Xinjiang.
But in Bangladesh, which has the world’s fourth biggest Muslim population, an Islamist group held a demonstration against China’s Muslim camps in front of the national mosque in the capital, Dhaka, on Sept. 7.
The group, Islami Andolan Bangladesh, threatened a Muslim boycott of Chinese products if Beijing didn’t release those detained.
In India, a Muslim organization called Raza Academy, which claims hundreds of thousands of followers, held a protest over China’s camps in Mumbai on Sept. 14.
About 150-200 Muslim scholars and community leaders took part, shouting “Stop using Chinese products” and carrying placards with messages such as “Chinese government must stop atrocities on Muslims.”
“The Communist government is forcing the Muslims to give up their faith,” said Mohammed Saeed Noori, Raza Academy’s general secretary. “It must stop.”