WASHINGTON: US President Donald Trump signed a revised ban on travelers from six Muslim-majority nations Monday -- one with a reduced scope so Iraqis and permanent US residents are exempt.

The White House said Trump signed the order -- which temporarily freezes new visas for Syrians, Iranians, Libyans, Somalis, Yemenis and Sudanese citizens -- behind closed doors "this morning".

The order places a 120 day freeze on all refugee arrivals.

The revised ban, which comes into effect on March 16, said the six countries were targeted because their screening and information capabilities could not meet US security requirements.

Officials said that, unlike in the initial January 27 executive order, all pre-existing, valid visas from the six countries would be honored.

"The motivating factor here is a desire for greater security," said a senior State Department official.

The Trump administration´s wide-ranging initial travel restrictions were slapped down by the federal courts, after sparking a legal, political and logistical furor.

The State Department cancelled 60,000 visas under the original order, and hundreds of people were reportedly detained at US airports.