WASHINGTON (BLOOMBERG) - US President Donald Trump said the United States might expand the travel ban affecting Europe and China as well as several other countries to include additional nations as the US extends its effort to prevent the spread of coronavirus.

"They'll be staying and we may add a few more," Mr Trump said at a White House press conference on Monday.

"But the guidelines will be very much as they are, maybe even toughened up a little bit. But they're having a big impact, they're having a tremendous impact."

The White House has already moved to block entry of non-US citizens travelling from China, Iran, the UK, Ireland, and 26 European countries in the Schengen Area that allow unrestricted movement among them.

The administration also struck agreements with the governments of Canada and Mexico to significantly scale back cross-border travel.

Mr Trump said officials were beginning to see the "impact" of the travel restrictions. On Sunday, he announced that federal social distancing guidelines set to expire this week would be extended until the end of April.