The United States (US) Supreme Court on Monday reinstated a ban on travellers from six mostly Muslim countries, overturning lower court orders that had blocked it.

The Trump administration had issued a controversial an executive order in January this year, banning all immigrants and visa holders from seven Muslim-majority countries from entering the US for 90 days. Later a revised order had excluded Iraq from the list. The ban would apply to citizens of Iran, Libya, Somalia, Sudan, Syria and Yemen.

The latest development is being dubbed as a victory for US President Donald Trump in the biggest legal controversy of his young presidency.

The court did leave one category of foreigners protected, those “with a credible claim of a bona fide relationship with a person or entity in the United States,” the court said in an unsigned opinion.

The justices will hear arguments in the case in October. Trump said last week that the ban would take effect 72 hours after being cleared by courts.

The Trump administration said the ban was needed to allow an internal review of the screening procedures for visa applicants from those countries. That review should be complete before October 2, the first day the justices could hear arguments in their new term.