Expats living in Australia could find themselves caught up in the confusion over the decision by American President Trump to deny entry to people from seven, mainly Muslim, countries in an immigration crackdown.

They are being advised that if they are looking to travel to the United States for work or to visit family and friends and they have a passport from, were born in, or have dual citizenship of the banned countries they may be turned back or even detained and questioned.

Donald-TrumpIt has created confusion for people with connections to the seven countries; Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen and despite worldwide condemnation the Department of Homeland Security has confirmed that the ban remains in place.

Those looking to travel to the US in the coming weeks who do not yet have a visa are likely to find that are unable to get one with the American Embassy and consulates in Australia already refusing applications. Students wishing to travel to the US could also be affected.

In one high profile case a schoolboy from Melbourne who was born in Australia but has dual Iranian citizenship has been refused a visa to go on a school trip to visit Orlando and Washington.

There is confusion at Australian airports as passengers with valid visas not allowed to board flights to the US and those that do facing not being allowed in to the US at the other end.

The Australian Government's Smarttraveller website has updated its notifications warning travellers to the US about the controversial new rules. It explains that citizens of the seven banned nations will no longer be allowed to apply for the standard electronic travel authorisation (ETSA) which travellers must complete before heading to the US.

The ETSA is an online application that determines entry eligibility based on security or police risks and even those who have previously been issued with an ETSA are likely to have it revoked.

Australian airline Qantas said that due to the change to US entry conditions it will try to help affected customers and offer refunds if necessary for people unable to travel who have already booked their flights while Virgin Australia is advising international travellers to ensure they have the documentation required to enter the US.

'Travellers are advised that visa and other entry and exit conditions can change at short notice. Travellers should contact the nearest Embassy or Consulate of the United States for the most current information,' said an Australian Foreign Office spokesman.

'The Australian Embassy in Washington is engaging with US officials on the potential implications of the suspension for Australian travellers, including dual nationals,' he added.