Washington DC - A federal judge on Wednesday blocked Donald Trump's attempt to restrict birthright citizenship in the US in a blow to the president's bid to end a right enshrined in the Constitution for more than a century.

The ruling indefinitely bans enforcement of one of Trump's most controversial executive orders, which was due to come into effect nationwide on February 19.

"The denial of the precious right to citizenship will cause irreparable harm," District Judge Deborah Boardman was reported as saying during the hearing at a Maryland court.

She noted that Supreme Court precedent protects birthright citizenship, adding that Trump's order "conflicts with the plain language of the 14th Amendment," the Washington Post reported.

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"No court in the country has ever endorsed the president's interpretation," she said.

"This court will not be the first."

The injunction adds to a 14-day stay on enforcement of Trump's executive order issued in January by a federal judge in Washington state.

There, US District Judge John Coughenour condemned the order as "blatantly unconstitutional," though Trump quickly told reporters he planned to appeal the ruling.