A federal judge said on Monday that she would issue a brief extension of an order temporarily blocking United States President Donald Trump’s plan to bar foreign nationals from entering the US to study at Harvard University while she decides whether to issue a longer-term injunction.

US District Judge Allison Burroughs, at the end of a hearing in Boston in Harvard’s legal challenge to the restrictions, extended to June 23 a temporary restraining order that had been set to expire on Thursday. She said she wanted to give herself more time to prepare a ruling.

“We’ll kick out an opinion as soon as we can,” she said.

Ian Gershengorn, a lawyer for Harvard, told her that an injunction was necessary to ensure Trump’s administration could not implement his latest bid to curtail the school’s ability to host international students.

The judge scheduled the hearing after issuing a temporary restraining order on June 6, preventing the administration from implementing a proclamation that Trump had signed a day earlier. A preliminary injunction would provide longer-term relief to Harvard.

Gershengorn argued that Trump signed the proclamation to retaliate against Harvard in violation of its free speech rights under the US Constitution’s First Amendment for refusing to accede to his administration’s demands to control the school’s governance, curriculum and the ideology of its faculty and students.

“The proclamation is a plain violation of the First Amendment,” Gershengorn said.

Almost 6,800 international students attended Harvard in its most recent school year, making up about 27 per cent of the student population of the prestigious school located in Cambridge, Massachusetts. China and India are among the top countries of origin for these students.

The Trump administration has launched a multifront attack on the oldest and wealthiest US university, freezing billions of dollars in grants and other funding and proposing to end its tax-exempt status, prompting a series of legal challenges.

Harvard has filed two separate lawsuits before Burroughs seeking to unfreeze $2.5 billion in funding and to prevent Trump’s administration from blocking the ability of international students to attend the university.

Homeland Security Secretary Kristi Noem on May 22 announced that her department was immediately revoking Harvard’s Student and Exchange Visitor Programme certification, the governmental mechanism that allows it to enrol foreign students.

Her action was almost immediately blocked by Burroughs. While the Department of Homeland Security has since shifted to challenging Harvard’s certification through a lengthier administrative process, Burroughs at a May 29 hearing said she planned to issue a “broad” injunction to maintain the status quo.

A week later, though, Trump signed his proclamation, which cited national security concerns to contend that Harvard is “no longer a trustworthy steward of international student and exchange visitor programmes”.

The proclamation suspended the entry of foreign nationals to study at Harvard or participate in exchange visitor programmes for an initial period of six months and directed Secretary of State Marco Rubio to consider whether to revoke visas of international students already enrolled at Harvard.

Harvard has asked Burroughs, an appointee of Democratic President Barack Obama, to block Trump’s directive.

In court papers, the US Justice Department urged Burroughs not to lump Trump’s proclamation in with the judge’s consideration of Noem’s actions, as it did not ban existing students and Trump relied on different legal authority for his order.