Ramadan, who is from Switzerland, filed for the visa after being invited to teach at the University of Notre Dame, but was rejected after it emerged that he supported an organization later deemed a terrorist front, the New York Sun reported Tuesday.

The American Civil Liberties Union has been working since fall to have a federal judge review the reasons for Ramadan's exclusion from the country. The ACLU claims he was denied a visa because he criticized American foreign policy.

"In our view the government's stated reason for excluding him is just a pretext," the director of the ACLU's National Security Project, Jameel Jaffer, said.

He added Ramadan was not aware the organization to which he donated was connected with terrorism.