A judge has issued a temporary restraining order ruling that the Trump administration cannot bar international students at Harvard from entering the U.S.

A federal judge blocked the Trump administration's move to revoke Harvard's visa program, halting a plan critics say could jeopardize international students and escalate court battles.

A group of 18 leading US research universities, including Princeton, MIT, Caltech and Johns Hopkins, asked a federal judge for permission to file legal arguments in support of Harvard University in its high-stakes showdown with the Trump administration over more than $2 billion in frozen grant money.