U.S. President Donald Trump on Thursday voiced his opposition to any salary rise for federal employees, prompting a bipartisan backlash.

"I have determined that for 2019, both across-the-board pay increases and locality pay increases will be set at zero," Trump said in a letter to House Speaker Paul Ryan.

Trump said the planned locality pay increase of 25.7 percent and across the board pay increase of 2.1 percent could not be sustained by Federal budgets.

The locality pay increase alone would cost 25 billion U.S. dollars, he said.

Trump said he is exercising power to stall pay rises in cases of "national emergency or serious economic conditions affecting the general welfare."

The move has sparked a backlash from both Democratic and Republican Congress members, criticizing Trump for blocking pay raise for civilian employees.

Republican Representative Barbara Comstock of Virginia said the government should support federal workers.

"Dedicated work is also done by our civilian employees at other national security agencies," she said.

Analysts believed that Congress may grant the pay raise regardless of Trump's advice.

The Senate Appropriations Committee has included a 1.9 percent pay raise in its spending plan for 2019, it will consult with the House to produce a final version in the coming weeks.