President Donald Trump has renewed his attacks on the judiciary for considering legal challenge to his controversial travel ban, describing the process as "disgraceful" and courts ruling on the issue as "political."

Addressing a law enforcement conference in Washington on 8 February, Trump harshly criticised Tuesday's hearing, in which three judges heard the appeal against Trump's executive order, banning people from seven predominantly Muslim countries entering the US.

"I won't say the court was biased. But so political," he said.

Seemingly offering his own legal arguments, Trump said that US presidents had wide ranging authority to determine who entered the country. Reading from a US immigration law document he declared even a "bad high school student" could understand it and would vote in his favour.

The California-based 9th Circuit Court of Appeals will decide in days whether to reinstate the order that bars all refugees entering the country, and all citizens from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen entering the country for 90 days.

The ban was suspended and visas reinstated after Judge James Robart ruled on Friday that there were grounds to challenge the order.

"I listened to a bunch of stuff last night on television that was disgraceful," Trump said. "I think it's sad. I think it's a sad day. I think our security is at risk today."

Mr Trump went on: "I listened to lawyers on both sides last night, they were talking about things that had nothing to do with it.

"It's so sad when you read something so perfectly written and so clear to anybody. I watched last night in amazement and I heard things I couldn't believe.

"I don't ever want to call a court biased so I won't call it biased, and we haven't had a decision yet, but courts seem to be so political.

"But it would be so great for our system if they could read something and do what's right."