The White House said on Friday it had begun mass lay-offs of federal workers as US President Donald Trump sought to amp up pressure on opposition Democrats to end a government shutdown that has crippled public services.

With the crisis set to go into a third week and no off-ramp in sight, Trump’s budget chief Russ Vought confirmed on social media that the administration had begun following through on its threat to begin firing some of the 750,000 public servants placed on enforced leave.

The Office of Management and Budget, headed by Vought, said the lay-offs would be “substantial”, but gave no precise numbers or details of which departments would be most affected.

The announcement came days after Trump said he was meeting Vought to determine which agencies “he recommends to be cut, and whether or not those cuts will be temporary or permanent”.

The president has repeatedly emphasised that he views cutbacks as a way of increasing pain on Democrats.

Senate Democratic Leader Chuck Schumer and his House counterpart Hakeem Jeffries have dismissed the job cuts threat as an attempt at intimidation and said mass firings would not stand up in court.