Federal officials told a judge Friday they will not release Mahmoud Khalil, a Palestinian student the administration is trying to deport, saying they have legal reasons to keep him in detention.

A judge earlier this week had struck down one of the administration’s justifications for detaining and trying to deport Mr. Khalil — that his pro-Palestinian activities at Columbia University interfered with U.S. foreign policy.

But the Justice Department said Friday that the government believes it has other valid reasons for detaining Mr. Khalil based on erroneous statements he made in an application for a green card, or lawful resident status.

August E. Flentje, a Justice Department lawyer, said if Mr. Khalil wants to contest that, he will need to do so in arguments to Homeland Security and then in an immigration courtroom.

“These administrative processes are the proper avenues for Khalil to seek release — not having a federal​ district court hold that the government cannot detain Khalil on a charge that the court never found​ to be unlawful,” Mr. Flentje said.

Mr. Khalil’s lawyers had been prodding Judge Michael Farbiarz to order Mr. Khalil’s release, after the judge issued his ruling earlier this week.

In that decision, the judge struck down the foreign policy explanation for detaining Mr. Khalil as unconstitutionally vague. And he said the other argument the government made about the erroneous application, while perhaps eventually a valid reason for deportation, is almost never a justification for detaining someone.

Mr. Flentje, though, said the judge never actually ruled it illegal.

“An alien like Khalil may be detained during the pendency of removal proceedings regardless of the charge of removability,” Mr. Flentje said.

Mr. Khalil’s lawyers have asked Judge Farbiarz to order his outright release. They said Mr. Khalil has already posted bond.

Mr. Khalil’s case has been one of the most prominent challenges to the Trump administration.

He is being held in immigration detention in Louisiana and missed the birth of his baby. He says U.S. Immigration and Customs Enforcement has even tried to block him from holding the child during visits with his wife.

Mr. Flentje said if the court does now go further and order release, the government would seek to overturn that ruling.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.