A US judge has temporarily blocked construction from starting on President Donald Trump's proposed 76-metre triumphal arch in Washington, shortly after it won a key approval.

District Judge Tanya Chutkan issued a 14-day restraining order late on Thursday following the National Capital Planning Commission voting by an eight-to-four margin to approve the project after it heard from about 100 opponents, including Democratic lawmakers.

The Trump administration contends Congress approved the arch more than 100 years ago when it also authorised construction of a bridge across the Potomac River.

"The sheer improbability that a 100-year-old statute would contain authority, unknown to every previous administration, to erect a 250-foot arch at a principal location in the nation’s capital indicates how far [the government] must stretch to justify this project," Chutkan wrote.

She said approval would result in construction for about three years "that will disrupt traffic, create noise, result in large-scale excavation, and more."

The Justice Department had said earlier that if the project had been approved it expected an initial six to eight months of construction focused on excavation and foundation work could begin as soon as Thursday. Above-ground construction would start in May 2027 at the earliest, with the job expected to take 33 to 39 months total.

"It will snarl traffic for years, impact the nearby airport, and present even more serious threats to public safety that this commission has refused to acknowledge and grapple with," said Representative Don Beyer, a Democrat who represents northern Virginia.

The National Park Service also said late on Thursday it had approved the project.

The arch is among several costly projects Trump is pushing in Washington despite opposition from local officials and conservationists. They include rebuilding the Reflecting Pool at the Lincoln Memorial, constructing a massive White House ballroom and overhauling the Kennedy Center for the Performing Arts.

The arch has faced significant opposition in the courts. The state of Virginia and the District of Columbia sued the National Park Service and the Department of the Interior on Saturday, seeking to halt the start of construction, calling it "legally indefensible" and arguing that Congress has not approved it.

The arch would resemble the Arc de Triomphe in Paris but stand more than 24 metres taller. It would also be nearly as tall as the US Capitol, which at 87 metres, can be seen across much of Washington. The site is near airplanes' final approach to Ronald Reagan Washington National Airport.

A rendering showed the flame would be held by a 18-metre-tall gold, winged female figure positioned atop the arch and flanked by gold flying eagles. (Reuters)


Edited by Aaron Tam