Washington DC - Agriculture Secretary Brooke Rollins on Thursday slammed the Mexican government for what she sees as an inadequate reaction to the spread of the New World screw worm.

Tension has mounted between the Trump administration and President Claudia Sheinbaum's government over protocols to stop the spread of the New World screw worm into the US.

Earlier this week, a screw worm was detected less than 70 miles from the US border. Rollings blamed the discovery on the failure to control the movement of cattle and inadequate fly traps.

The screw worm is the larva of a parasitic blowfly that eats the tissue of warm-blooded animals. It is considered a serious biosecurity threat and was eradicated from North America in the early 2000s.

"Unfortunately, what we found is Mexico has failed to enforce proper cattle movement controls in infected regions and is not tending to fly traps daily as promised," Rollins said on Thursday. "This is unacceptable."

Rollins said that the border would not be reopened to livestock until Mexican authorities can prove that they have complied with all biosecurity protocols.

On Wednesday, following the initial discovery, Rollins announced that the Department of Agriculture had immediately released 80,000 sterile flies to try controlling the spread of screw worm.

"Under President Trump’s leadership, USDA is moving fast to defend our ranchers, our beef supply, and our national security," she said on X.

Mexico's sanitation agency Senasica responded to Rollins' comments by insisting that it had been abiding by protocols agreed on by both countries.

"Regarding the detection of a case of New World screw worm in northern Mexico, it should be noted that this finding was possible thanks to the application of a protocol established in the bilateral action plan," Senasica told Reuters.