Donald Trump’s latest travel ban could cause problems to seafarers of targeted nationalities, a New York-based law firm says.

The revised order signed by the US president yesterday introduces restrictions on travel to the US from Iran, Libya, Somalia, Sudan, Syria and Yemen.

Nationals from those countries will be denied entry for 90 days from 16 March, so crew on ships visiting US ports will not be able to obtain visas in that period.

They will not be allowed to enter the country if they were outside the US on 16 March and did not hold a valid visa as of 27 January.

Law firm Freehill, Hogan & Mahar said: “If a vessel arrives at a US port with crew from any of the six designated countries who do not have valid visas, those crew members will not be permitted to leave the vessel and it can be anticipated that the US authorities may well order that armed guards be placed at the vessel’s gangway to prevent any such crew from departing the vessel.”

If any seafarer’s visa expires after 16 March, then a new one must be applied for, it added.

Trump’s latest executive order is a revised version of a previous ban imposed in January that also included Iraq.