US data shows the number of Australians and others travelling to America has dropped steeply amid growing horror stories of people being subjected to extreme vetting at airports, including having their laptops and smartphones examined and being detained for many hours or deported.

Travel industry veterans, who asked to remain anonymous because they fear jeopardising their ability to transit through America, said they were “chilled to the bone” by how US border officials were treating an increasing number of travellers, and compared controls under Donald Trump to Iran, North Korea and Saudi Arabia.