US President Donald Trump defended his administration's move to block Harvard University's ability to enrol international students after a judge suspended the action.

A federal judge blocked President Trump's order banning international students at Harvard, but the effort has prompted concern at campuses nationwide among students and university leaders.

Harvard has called the Trump order a "blatant violation" of the US Constitution’s First Amendment and other federal laws. , US News News - Times Now

In a sharply worded letter, Homeland Security Secretary Kristi Noem notified Harvard that its SEVP certification was “revoked effective immediately.”

"We want to know who those foreign students are, a reasonable request since we give Harvard BILLIONS OF DOLLARS, but Harvard isn’t exactly forthcoming," he said. "We want those names and countries. Harvard has $52,000,000, use it, and stop asking for the Federal Government to continue GRANTING money to you!"

Trump stated that nearly 31 per cent of Harvard’s students come from other countries, and the university administration has not provided details about these students despite repeated requests from his

"It would be devastating," a former president of Harvard — and frequent critic of the university — said of the government's attempt to prevent Harvard from enrolling foreign students.

Eighteen people were injured in a knife attack in Hamburg station on Friday evening, Germany's Bild newspaper reported, and local police confirmed they had arrested the suspected assailant.

Beyond the shock for students, President Trump’s moves against higher education are being seen in China as a blow to one of the last admirable American institutions.

The Trump administration’s sudden move to bar foreign students at Harvard University is seen as dealing a blow to the US’s standing in business — and handing an advantage to elite rival colleges across the English-speaking world.