US President Donald Trump said that civilian employees of the federal government will not receive raises in 2019.

In doing away with the 2.1 per cent across-the-board pay increase that was scheduled to take effect in January, Trump said he was working "put our nation on a fiscally sustainable course."

Scrapping the raises will save more than $25 billion, Trump said.

"I have determined that for 2019, both across the board pay increases and locality pay increases will be set at zero," the US president said in a letter addressed to Speaker of the House Paul Ryan, and released by the White House. "These alternative pay plan decisions will not materially affect our ability to attract and retain a well qualified Federal workforce."