U.S. President Donald Trump brandished a document on Tuesday confirming details of a regional asylum project agreed with Mexico to stave off threatened tariffs, saying the plan was "secret" even though Mexican officials had revealed much of it.

Republicans are deeply concerned that Trump’s proposed 5 per cent tariffs on all imports from Mexico would spike U.S. consumers’ costs, harm the economy and imperil a major pending US-Mexico-Canada trade deal.

President Donald Trump has threatened to impose punitive tariffs of 5 per cent on Mexican goods, that would gradually increase to 25 per cent, if Mexico did not stem migration north.