One of Donald Trump's most senior advisers may have broken the law by endorsing his daughter's brands on live TV.

Kellyanne Conway discussed the President's tweet to Nordstrom - one of the retailers that has dropped Ivanka Trump's products - on the Fox & Friends program.

Mr Trump was accused of "abusing" the presidency after his public outburst about the company on Twitter, which was retweeted by the official @POTUS account.

Despite the furore shares in the chain of department stores, rose after his admonishment.

Ms Conway twice praised Ms Trump as a "very successful businesswoman", but said she had "obviously stepped away from it now".

Later, she said: "Go buy Ivanka's stuff, is what I would say. It's a wonderful line, I own some of it. I'm going to give a free commercial here, go buy it today."

Ms Conway appeared to be standing inside the White House press briefing room as she made her remarks.

Larry Noble, the general counsel for the Campaign Legal Centre, a nonpartisan organisation based in Washington DC, immediately suggested she had broken the law.

"Appears Kellayanne Conway may have just violated ban on Federal employee using public office for endorsement of product," he tweeted.

The statute he cited, 5 CFR 2635.702, addresses the "use of public office for private gain". Part (c) states: "An employee shall not use or permit the use of his Government position or title or any authority associated with his public office to endorse any product, service or enterprise", except in certain circumstances.

Mr Trump had lashed out at Nordstrom after it dropped his daughter's line of apparel.

He tweeted: "My daughter Ivanka has been treated so unfairly by @Nordstrom. She is a great person -- always pushing me to do the right thing! Terrible".

Nordstrom, which previously sold 71 Ivanka Trump items, has not bought any stock for 2017 and currently has only three lines of her shoes on its website.

Press secretary Sean Spicer later said: "I think this was less about his family business and was an attack on his daughter.

"He ran for president, he won, he’s leading this country, and I think for people to take out their concern on his action or his executive orders, on members of his family, [then] he has every right to stand up for his family and applaud their business activities [and] their success."