WASHINGTON — The Trump administration on Wednesday announced a ban on imports of cotton and tomatoes from the Xinjiang area of China, as well as all products made with those materials, citing human rights violations and the widespread use of forced labor in the region.

The measure could have sweeping implications for makers of apparel and food products, many of whom have sought to distance themselves from atrocities in Xinjiang but have struggled to ensure their supply chains are free of all raw materials from the region. The area is a major source of cotton, coal, chemicals, sugar, tomatoes and polysilicon, a component in solar panels, that are then fed into factories around China and the world.

The ban allows customs officials to stop imports that they suspect are made with raw materials from Xinjiang, regardless of whether they travel into the United States directly from China or through another country.

China has carried out a vast crackdown on predominantly Muslim minority groups in the far west Xinjiang region, including detaining a million or more Uighurs, Kazakhs and other groups in camps and closely surveilling the rest of the population, human rights groups say.

Forced labor also appears to be widespread in the region. The U.S. Customs and Border Protection said an investigation found numerous indicators of forced labor in Xinjiang, including debt bondage, restriction of movement, withheld wages, and abusive living and working conditions. The Chinese government denies the existence of forced labor in Xinjiang, saying all arrangements are voluntary.

Scott Nova, the executive director of the Workers Rights Consortium, a labor rights group, called the ban “a high-decibel wake-up call to any apparel brand that continues to deny the prevalence and problem of forced-labor-produced cotton” in the region.

“This ban will redefine how the apparel industry — from Amazon to Nike to Zara — sources its materials and labor,” Mr. Nova said. “Any global apparel brand that is not either out of Xinjiang already or plotting a very swift exit is courting legal and reputational disaster.”

The Workers Rights Consortium estimates that American brands and retailers import more than 1.5 billion garments that use Xinjiang materials every year, representing more than $20 billion in retail sales. China is also the world’s largest tomato producer, with Xinjiang accounting for most of that production, the group says.

Independent researchers and media reports have linked dozens of the world’s most prominent multinational companies to workers or products from Xinjiang, including Apple, Nike, Kraft Heinz and Campbell Soup. Campbell said it no longer sources products from the Xinjiang region.

Some textile and apparel companies that used cotton or yarn from Xinjiang have announced that they are severing ties, including Patagonia, Marks and Spencer and H&M. But many firms have found it difficult to trace the origins of all the products used by their Chinese suppliers, especially given the lack of access for independent auditors to facilities in Xinjiang.

The order will “send a crystal-clear message to the trade community: know your supply chains,” said Mark Morgan, the acting commissioner for U.S. Customs and Border Protection. Importers are required to ensure that their own supply chains are free from forced labor, he added. “It’s the law.”

The Trump administration has added increasingly restrictive measures on Xinjiang, including placing sanctions on dozens of companies and individuals over alleged human rights violations.

In December, customs officials announced a ban on cotton products made by the Xinjiang Production and Construction Corps, an economic and paramilitary group that produces much of the region’s cotton. U.S. Customs and Border Protection has already detained 43 shipments valued at more than $2 million under that ban, officials said Wednesday.

Congress is also considering sweeping legislation that would block imports from Xinjiang, unless companies are able to prove that supply chains that run through the region are free of forced labor.

While the United States has taken the most forceful action on this front, both Canada and Britain introduced rules this week to limit goods linked to Xinjiang from entering their countries.

Despite growing concerns over Chinese practices in the region, exports from Xinjiang to the United States and Europe grew significantly from 2019 to 2020, according to the Center for Strategic and International Studies.

But trade experts say the new measures will raise questions about whether customs officials are equipped to fully enforce such a wide ban, which will require tracing Xinjiang materials through supply chains around the world.

A report published in October by the U.S. Government Accountability Office found that customs suffered from staff shortages and other issues despite a new division and resources devoted to blocking goods made with forced labor.

In a call with reporters on Wednesday, Brenda Smith, the executive assistant commissioner at Customs and Border Protection’s Office of Trade, said it was “a challenge to be able to link what we see arriving in a port of entry back to the raw materials produced in Xinjiang.” The department is applying new tracking methods to uncover products made with forced labor, she said.

The department is increasingly making use of new technologies, like pollen analysis, to try to identify cotton and other materials from Xinjiang in foreign products, officials said.