Donald Trump fires acting Attorney-General

US President Donald Trump has replaced acting Attorney-General Sally Yates, the same day she said the Department of Justice wouldn't defend his travel restrictions targeting people from seven Muslim-majority countries.

Mr Trump has appointed Dana Boente, currently Attorney for the Eastern District of Virginia, as the new acting Attorney-General.

"Sally Yates has been relieved," Mr Trump's press secretary Sean Spicer tweeted.

Earlier today, Ms Yates, a Democratic appointee, brought into question the legality of Mr Trump's controversial travel ban.

In a letter to Department of Justice lawyers, she said she's not convinced Mr Trump's executive order is actually lawful.

In a statement, the White House says Ms Yates "betrayed" the Department of Justice and attacked her as being "weak on borders and very weak on illegal immigration".

"It is time to get serious about protecting our country. Calling for tougher vetting for individuals travelling from seven dangerous places is not extreme. It is reasonable and necessary to protect our community," the statement reads.

Mr Boente will take on the acting Attorney-General role until Senator Jeff Sessions is confirmed by the Senate for the job.

The order created mass chaos at airports with those in transit as it came into force at the weekend.

There were also mass protests.

Mr Trump's administration defended it, saying only 109 people of 325,000 who entered the US over a 24 hour period were detained and questioned.

Meanwhile, New Zealand Foreign Affairs Minister Murray McCully says he's still "seeking clarification" on what the decision means for dual Kiwi citizens.