Samantha Bee apologises for calling Ivanka Trump a 'feckless c**t'

US television host Samantha Bee has apologised for "crossing a line" by calling Ivanka Trump the C-word.

The vulgar slur was used in a Full Frontal segment about the Trump administration's controversial policy of separating children from their parents if it's believed they're trying to enter the US illegally.

Bee was one of many people who criticised Ivanka for posting a photo of her and her son online as the controversy raged on.

"You know, Ivanka, that's a beautiful photo of you and your child but let me just say, one mother to another: Do something about your dad's immigration practices, you feckless c**t," she said.

"Put on something tight and low-cut and tell your father to f**king stop it. Tell him it was an Obama thing and see how it goes."

The White House demanded an apology from Bee over the comments, which it received.

"I would like to sincerely apologise to Ivanka Trump and to my viewers for using an expletive on my show to describe her last night," said Bee on Twitter.

"It was inappropriate and inexcusable. I crossed a line, and I deeply regret it."

Right-wing commentators in the US have been quick to point out a perceived "double standard" in the reaction to Bee's comments, when compared to racist comments made by Roseanne Barr earlier this week.

Her show Roseanne was cancelled after she took to Twitter to say that Obama aide Valerie Jarrett - an African-American woman - was the offspring of the Muslim Brotherhood and Planet of the Apes.

US President Donald Trump responded to the controversy by speaking about himself in the third-person and asking when he'd get an apology over "horrible" comments made about him.

White House press secretary Sarah Huckabee Sanders also released a statement over the Full Frontal segment, which incorrectly alleges a "collective silence" about the slur, despite widespread condemnation.

"The language used by Samantha Bee last night is vile and vicious. The collective silence by the left and its media allies is appalling," she said in a statement.

"Her disgusting comments and show are not fit for broadcast, and executives at Time Warner and TBS must demonstrate that such explicit profanity about female members of this administration will not be condoned on its network."

TBS, the network that broadcasts Bee's Full Frontal, has also issued an apology on Twitter.

Bee has also had supporters, including acclaimed 71-year-old actor Sally Field, who claimed "c**t" was too kind a word for Ivanka.