The White House is expected to announce that the US will broaden its European travel ban, adding the United Kingdom and Ireland to its list.

Under the restrictions, American citizens, green card holders and others are still allowed to return home to the US - but will be funnelled to 13 airports and be subjected to health screenings and quarantine orders, according to reports.

On Wednesday, President Trump announced a month-long restriction on travel from most of Europe, set to begin at midnight on Friday night.

He said on Thursday that he was considering other major restrictions, such as limiting travel to domestic hot spots like California and Washington state, without spelling out how he would manage such an extraordinary effort.

The State Department issued a global advisory cautioning US citizens to "reconsider travel abroad".