Senator Robert Menendez, the top Democrat on the Senate Foreign Relations Committee, had used his powers to block sales of tens of thousands of precision-guided bombs to Saudi Arabia and the United Arab Emirates, fearing they would contribute to the humanitarian crisis in Yemen, where the US allies are mounting an offensive.

But the administration informed lawmakers that it was bypassing a legally required review by Congress to approve the sales as part of a total of 22 arms transactions to Saudi Arabia, the United Arab Emirates and other nations, Menendez's office said.

"I am disappointed, but not surprised, that the Trump administration has failed once again to prioritize our long-term national security interests or stand up for human rights, and instead is granting favors to authoritarian countries like Saudi Arabia," Menendez said in a statement.

"With this move, the president is destroying the productive and decades-long working relationship on arms sales between the Congress and the executive branch," he said.

"The possible consequences of this decision will ultimately threaten the ability of the US defense industry to export arms in a manner that is both expeditious and responsible," he said.

The sales come after Trump vetoed a move by Congress to stop US support for the Saudi-led war in Yemen, where tens of thousands have died and millions risk starvation in what the United Nations calls the world's biggest humanitarian crisis.

Secretary of State Mike Pompeo has resolutely defended the US support for the Saudis, noting that the Huthi rebels who control much of Yemen are allied with US adversary Iran and saying that Huthi rocket attacks into Saudi Arabia could kill Americans taking commercial flights.