A ransomware attack on the world's largest meat processing company disrupted production around the world just weeks after a similar incident shut down a U.S. oil pipeline.

Brazil's JBS, however, said late Tuesday that it had made "significant progress" in dealing with the cyberattack and expects the "vast majority" of its plants to be operating on Wednesday.

"Our systems are coming back online and we are not sparing any resources to fight this threat," Andre Nogueira, CEO of JBS USA, said in a statement.

Earlier, the White House said JBS had notified the U.S. of a ransom demand from a criminal organization likely based in Russia. White House principal deputy press secretary Karine Jean-Pierre said the White House and the Department of Agriculture have been in touch with the company several times this week.

There is no reported response from Russia so far. 

JBS is the second-largest producer of beef, pork and chicken in the U.S. If it were to shut down for even one day, the U.S. would lose almost a quarter of its beef-processing capacity, or the equivalent of 20,000 beef cows, according to Trey Malone, an assistant professor of agriculture at Michigan State University.

The closures reflect the reality that modern meat processing plants are heavily automated, for both food- and worker-safety reasons. Computers collect data at multiple stages of the production process, and orders, billing, shipping and other functions are all electronic.

JBS, which has not stated publicly that the attack was ransomware, said the cyberattack affected servers supporting its operations in North America and Australia. Backup servers weren't affected and it said it was not aware of any customer, supplier or employee data being compromised.

Malone said the disruption could further raise meat prices ahead of summer barbecues. Even before the attack, U.S. meat prices were rising due to coronavirus shutdowns, bad weather and high plant absenteeism. The U.S. Department of Agriculture (USDA) has said it expects beef prices to climb 1 percent to 2 percent this year, poultry as much as 1.5 percent and pork between by from 2 percent and 3 percent.

JBS, which is a majority shareholder of Pilgrim's Pride, didn't say which of its 84 U.S. facilities were closed Monday and Tuesday because of the attack. It said JBS USA and Pilgrim's were able to ship meat from nearly all of its facilities Tuesday. The company also said it was making progress toward resuming plant operations in the U.S. and Australia. Several of the company's pork, poultry and prepared foods plants were operational Tuesday and its Canada beef facility resumed production, it said.

Earlier Tuesday, a union official confirmed that two shifts at the company's largest U.S. beef plant, in Greeley, Colorado, were canceled. Some plant shifts in Canada were also canceled Monday and Tuesday, according to JBS Facebook posts.

In Australia, thousands of meat plant workers had no work for a second day Tuesday, and a government minister said it might be days before production resumes. JBS is Australia's largest meat and food processing company, with 47 facilities across the country including slaughterhouses, feedlots and meat processing sites. 

In addition, USDA has spoken to several major meat processors in the U.S. to alert them to the situation, and the White House is assessing any potential impact on the nation's meat supply.

JBS has more than 150,000 employees worldwide.