A US appeals court in San Francisco has denied an emergency motion filed by the justice department to reinstate President Donald Trump's halted immigration ban.

The justice department filed an appeal late on Saturday to restore an executive order barring citizens from seven mainly Muslim countries and temporarily banning refugees, even as travellers raced to enter the country while the ban was lifted.

The appeal aimed to reverse a federal judge's Friday order that lifted the travel ban, warning the decision posed an immediate harm to the public.

The state department said last week that up to 60 000 people had their visas revoked as a result of Trump's ban, although a justice department lawyer put the number at closer to 100 000.

The restrictions on all refugees and travellers from the seven countries went into effect a week ago, wreaking havoc at airports across the US and leaving travellers trying to reach the country in limbo.

The political backlash for Trump has been equally severe, with the order driving numerous mass protests.