WASHINGTON — President Trump on Tuesday declared meat processing plants “critical infrastructure,” in an effort to ensure that facilities around the country remained open as the government tried to prevent looming shortages of pork, chicken and other products as a result of the coronavirus.

The action comes as meat plants around the country have turned into coronavirus hot spots, sickening thousands of workers, and after the head of Tyson Foods, one of the country’s largest processors, warned that millions of pounds of meat would simply disappear from the supply chain.

In an executive order issued late Tuesday, Mr. Trump said recent closures of meat processing facilities “threaten the continued functioning of the national meat and poultry supply chain, undermining critical infrastructure during the national emergency.”