A US appeals court on Monday left in place a block on President Donald Trump's travel ban targeting citizens from six Muslim majority nations -- the latest in a string of judicial blows for the controversial measure.

The US Court of Appeals for the Ninth Circuit largely upheld an injunction on the ban issued by a lower court, but however said the government was within its right to review the vetting process for people entering the country.

"Immigration, even for the president, is not a one-person show," the ruling said. "The president, in issuing the executive order, exceeded the scope of the authority delegated to him by Congress."