donald trump
President Donald Trump addresses the Project Safe Neighborhoods National Conference on December 07, 2018 in Kansas City, Missouri. Trump delivered the closing address speaking about the department's strategy for reducing violent crime.Jamie Squire/Getty Images [Representational Image]

US President Donald Trump has backed plans to request $750 billion from Congress for defence spending next year, a U.S. official said on Sunday, signalling a Pentagon spending hike at a time of potential belt-tightening elsewhere in the government.

Trump, faced with a budget deficit at a six-year high, told his Cabinet earlier this year to come up with proposals to cut spending by their agencies by 5 percent, but he suggested the military would be largely spared.

The $750 billion would be even more than the $733 billion request that the Pentagon had been expected to make for the fiscal year 2020. It is also well above a $700 billion figure Trump cited in October.

A U.S. official, speaking on condition of anonymity, said Defense Secretary Jim Mattis had discussed the budget with Trump in recent days and outlined the risks of flat defence spending.

The official said that it was clear during that discussion that Trump wanted to "accelerate the progress his administration has made in rebuilding the military."

In August, Trump signed a $716 billion defence policy bill.

The White House did not immediately respond to a request for comment.