Federal judges expressed scepticism Tuesday over the need for President Donald Trump's travel ban, which has upended travel to the US for more than a week and tested the new administration's use of executive power, a report said.

The US Justice Department asked the appeals court to restore Trump's order, contending that the president alone has the power to decide who can enter or stay in the country, reported TIME.

Several states have challenged the ban on travellers from seven Muslim majority nations, stressing that it is unconstitutional.

Circuit Judge Michelle T Friedland, who was appointed by President Barack Obama, asked whether the government has any evidence connecting the nations covered by the ban to terrorism.

August Flentje, special counsel to the assistant attorney general, said the government is aware of some foreign nationals who have been arrested in the US since Sept 11, without giving details of the evidence.

He also said president has broad power to enforce national security.

It was unlikely 9th US Circuit Court of Appeals would issue a ruling Tuesday, with a decision expected later this week, court spokesman David Madden said.

Whatever the court eventually decides, either side could ask the Supreme Court to intervene.