NEW YORK — Six states and the District of Columbia sued the Department of Agriculture on Wednesday, saying it weakened nutritional standards in school breakfasts and lunches when it relaxed the requirements affecting salt and refined grains last year.

The lawsuit in Manhattan federal court asked a judge to overturn the changes, saying they were carried out in an arbitrary and capricious manner.

The government "significantly weakened" nutritional standards for sodium and whole grains, according to the lawsuit, without giving the public a chance to comment on them and in opposition to nutritional requirements for school meals set by Congress.

The states and D.C. said the standards should be based on recommendations of the U.S. government's "Dietary Guidelines for Americans," the National Academy of Sciences and scientific research regarding children's nutrition.

The USDA school lunch program provides low-cost or free lunches and breakfasts in public schools and other institutions. Last year, it served an estimated 30 million children.

An email seeking comment was sent to the Justice Department.

New York Attorney General Letitia James led the multistate civil legal action, saying in a release that over a million children in New York depend daily on the meals.

"The Trump Administration has undermined key health benefits for our children — standards for salt and whole grains in school meals — with deliberate disregard for science, expert opinion, and the law," she said.

The other plaintiffs are California, Illinois, Minnesota, New Mexico, Vermont and the District of Columbia.

The lawsuit was filed after the Trump administration late last year scaled back contested school lunch standards implemented under the Obama administration, including one requiring that only whole grains be served.

At the time of the reversal, the Department of Agriculture said it wanted to reduce bureaucracy that required schools to get special waivers in order to serve select refined grains foods.

The changes made by the Trump administration also permitted low-fat chocolate milk to be served again where only fat-free milk had been permitted to be flavored.

The department has said 20% of schools last year applied for exemptions to the whole-grain rule, most frequently so they could serve pasta, tortillas, biscuits and grits.

The 2018 changes still required schools to reduce sodium in foods in stages, but they eliminated a final target for reduced sodium.