Harvard University said on Thursday that U.S. President Donald Trump's move to bar foreign nationals seeking to study at the Ivy League school from entering the United States is illegal, and asked a judge to block it immediately pending further litigation.

University files an amended complaint to a pending lawsuit in federal court amid an ongoing struggle between the nation’s president and the elite college.

On Wednesday, President Donald Trump signed a directive seeking to block U.S. entry for Harvard’s international students. It marked the administration’s latest effort to squeeze Harvard’s foreign enrollment after a federal judge in Boston blocked the withdrawal of its certification to host students from overseas.