U.S. Customs and Border Protection officials have prepared orders to block imports of cotton and tomato products from China’s western region of Xinjiang over accusations of forced labor, though a formal announcement has been delayed, Reuters reports.

The cotton and tomato bans, and those on five other imports, over alleged Xinjiang forced-labor abuses, would be an unprecedented move by the agency, likely to stoke tension between the world’s two largest economies.

The “Withhold Release Orders” let the agency detain shipments based on suspicion of forced-labor involvement under long-standing U.S. laws to combat human trafficking, child labor and other human rights abuses.

In Beijing on Wednesday, a foreign ministry spokesman dismissed the orders as a pretext to target Chinese firms. China will take all necessary measures to safeguard its companies’ legitimate rights and interests, he added.

CBP official Brenda Smith told Reuters the effective import bans would cover the entire supply chains for cotton, from yarn to textiles and apparel, as well as tomatoes, tomato paste and other regional exports.

“We have reasonable, but not conclusive, evidence that there is a risk of forced labor in supply chains related to cotton textiles and tomatoes coming out of Xinjiang,” Smith, an executive assistant commissioner, said in an interview. “We will continue to work our investigations to fill in those gaps.”

U.S. law requires the agency to detain shipments in cases of forced labor accusations, such as those from non-government bodies, she said.

The bans could have far-reaching effects for U.S. food manufacturers.