MADRID: President Donald Trump's executive order blocking immigrants from seven majority Muslim nations will hit tourism to the US, the UN's World Tourism Organization warned Wednesday.

The ban on nationals from Syria, Iraq, Iran, Sudan, Libya, Somalia and Yemen has triggered a domestic and international uproar, but supporters argue it is a temporary measure aimed at boosting national security.

In a statement, the Madrid-based UNWTO voiced "deep concern and strong condemnation" over the immigration clampdown.

The move is "contrary to the principles of freedom of travel" and will "hinder the immense benefits the tourism sector brings in terms of economic growth and job creation," added the agency.

Rather than increased security, the travel ban will lead to "growing tensions and threats," said UNWTO chief Taleb Rifai.

He added that "the image of a country which imposes travel bans in such a hostile way" would affect potential visitors the world over and "risk dumping travel demand to the USA."

Trump's executive order, which has also temporarily halted refugee arrivals, has seen immigrants and even legal permanent US residents detained in several airports.

Some were turned away and put on departing flights, but many were released into the US, often with the help of US attorneys, after a delay.

-AFP