U.S. President Donald Trump on Thursday signed a memorandum that requires universities to collect admissions data to prove they are not engaged in efforts to shape their student bodies along racial lines, according to the White House.

But the largest higher education policy and lobbying organisation in the U.S. said the wording of the memo was vague. The American Council on Education also said it may be illegal for schools to collect the data on race that the White House seeks.

The move is the latest effort in the Trump administration's effort to dismantle affirmative action policies at universities. It has launched dozens of investigations and threatened to cut off funding to schools that promote diversity, equity and inclusion programs.

According to the memorandum, a 2023 U.S. Supreme Court ruling knocked down the use of affirmative action in college admissions, but universities have skirted that decision by relying on "diversity statements" students provide in applying that indicate their race. The White House now wants schools to show they are complying.

The U.S. Department of Education said in a statement that Education Secretary Linda McMahon had directed the National Center for Education Statistics to collect from universities data on the race and gender of their applicant pool, on the students admitted and of all enrolled undergraduates.

Jonathan Fansmith, senior vice president at the American Council on Education, which represents 1,600 member schools, said collecting such data was illegal under the very Supreme Court ruling that ended affirmative action.

"You can't consider race in admissions, so schools don't collect data on race from applicants," Fansmith said. "This seems to be an effort to get institutions to provide information that we don't have and that we can't collect."

But a senior Trump administration official said the administration's understanding of the 2023 Supreme Court ruling on affirmative action was that nothing in it "prohibits the collection of demographic data as long as such data is not used in admissions decisions."

The official, who was not authorised to discuss the matter, spoke on the condition of anonymity.

The official went on to say that the administration expected universities to block access of their admissions officials to any data on the race of any applicant.