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

The Trump administration announcement of the actions, initially expected on Tuesday, has been put off until later this week because of “scheduling issues,” a CBP spokesman said.

The cotton and tomato bans along with five other import bans involving Xinjiang forced-labor abuses would be an unprecedented move by CBP and likely stoke tensions between the world’s two largest economies.

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

President Donald Trump’s administration is ratcheting up pressure on China over its treatment of Xinjiang’s Uighur Muslims. The United Nations has said it has credible reports that 1 million Muslims have been detained in camps in the region, where they are put to work.

China denies mistreatment of the Uighurs and says the camps are vocational training centers needed to fight extremism.

CBP Executive Assistant Commissioner Brenda Smith told Reuters that the effective import bans would apply to the entire supply chains involving cotton, including cotton yarn, textiles and apparel, as well as tomatoes, tomato paste and other products exported from the region.

“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 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 when there is an allegation of forced labor, such as from non-governmental organizations, she said.

Farmers dry tomatoes in Korla, in Xinjiang, in August 2014. The Second Division under the Xinjiang Production and Construction Corps, a semi-military administrative body in a few places of Xinjiang, has some of the best tomato farms in China.

US order blocking Xinjiang cotton, tomato imports delayed