By Mei Mei Chu

BEIJING, March 17 (Reuters) - Export registrations for more than 1,000 U.S. meat plants granted by China under the 2020 "Phase 1" trade deal lapsed on Sunday, China's customs website showed, threatening U.S. exports to the world's largest buyer amid an ongoing tariff standoff.

The registration status for pork, beef and poultry plants across the U.S., including major producers Tyson Foods TSN.N, Smithfield Packaged Meats and Cargill Meat Solutions was changed from "effective" to "expired", according to the website of China's General Administration of Customs.

The expiration of roughly two-thirds of the total registered facilities could restrict U.S. market access and incur significant losses to a roughly $5 billion trade, a fresh affront to American farmers after Beijing earlier this month imposed retaliatory tariffs on some $21 billion worth of American farm goods.

Beijing requires food exporters to register with customs to sell in China.

The U.S. Department of Agriculture has said China did not respond to repeated requests to renew plant registrations, potentially violating the Phase 1 trade agreement.

Under the Phase 1 trade deal, China is obligated to update its approved plant list within 20 days of receiving updates from the USDA.

Registrations for some 84 U.S. plants lapsed in February and while shipments from these affected plants continue to clear customs, the industry doesn't know for how long China will allow imports.

China's customs department did not immediately respond to faxed questions.

In 2024, the U.S. was China's third-largest meat supplier by volume, trailing Brazil and Argentina, accounting for 590,000 tons or 9% of China's total meat imports.

(Reporting by Mei Mei Chu; Editing by Lincoln Feast.)

((Ella.Cao@thomsonreuters.com;))