US President Donald Trump's temporary ban on refugees and travelers from six mainly Muslim countries came into effect, after the Supreme Court allowed it following a five month battle with rights groups.

The Trump administration said late yesterday the ban is necessary to block terrorists from entering the country, but immigrant advocates chargeed that it illegally singles out Muslims.

The 90-day ban on visitors from Iran, Libya, Somalia, Sudan, Syria and Yemen will allow exceptions for people with "close family relationships" in the United States, which the government has defined narrowly, excluding grandparents and grandchildren, aunts and uncles and others.