The number of top US government posts so far filled by President Donald Trump's administration is dramatically lower than for any of his four predecessors, latest figures show.

Five months since the inauguration vast swathes of the US government are being staffed by acting officials with new political appointments either still to be confirmed by the US Senate or not yet nominated by the White House.

At the State Department less than one in ten Trump appointments are in place with a host of ambassadors and senior diplomats yet to be assigned.

Former officials warned the delay would lead to a receding of US influence around the globe and a lower level of engagement with allies.