A US appeals court has upheld an order halting construction of President Donald Trump's proposed White House ballroom, ruling that the massive project requires explicit approval from Congress.

The US Court of Appeals for the District of Columbia Circuit ruled 2-1 that Trump's administration could not proceed with the project without congressional authorisation. The court temporarily stayed its ruling for two weeks, allowing the administration time to appeal to the Supreme Court.

Trump criticised the ruling as politically motivated, unlawful, describing the decision as a threat to national security. He said he would immediately challenge the ruling before the Supreme Court.

The proposed ballroom, initially estimated to cost $200m, has seen its projected cost rise to about $400m, with some reports putting the potential final cost as high as $600m. Trump has said the project would be privately financed, although reports indicate that taxpayer funds have also been used.

Construction began after the demolition of the White House's historic East Wing, a move that has faced legal challenges from preservation groups. The court said the ruling did not determine whether the ballroom should ultimately be built, only that construction could not proceed without the required congressional authorisation.

The case is expected to move to the Supreme Court, setting up a major legal dispute over the limits of presidential authority to alter the White House complex.