Donald Trump's campaign has been accused of changing the skin colour of a model wearing his election merchandise to make her appear black.
A photo on his campaign clothing store showed a black female model wearing a grey T-shirt - in an apparently identical shot to another clothing store photo in which the model is white.
The two images have prompted criticism and debate online among Mr Trump's supporters and opponents, with many resorting to heavy irony in their disbelief.
"Heaven forbid Trump would actually use someone of actual brown colour in their ads," one Twitter user wrote.
Another asked: "Is Trump's campaign tacitly admitting they have an ethnic problem?"
So it appears Donald Trump’s campaign photoshopped their model to be brown: pic.twitter.com/V0DghCiQAW— Eric Ming (@ericming5) March 3, 2016
The business mogul, who took seven states on Super Tuesday in a sweep that makes his path to the Republican nomination in the race for the White House difficult to derail, has called Mexicans "rapists" and said he would prevent all Muslims from entering the US.
He was also recently criticised by fellow Republican contender Marco Rubio for blaming a faulty earpiece on a refusal to disavow the Ku Klux Klan.
Asked about support given him by former "Grand Wizard" of the white supremacist group David Duke, Mr Trump repeatedly said he "didn't know" and then later said a "lousy earpiece" had prevented him condemning the group.
Twitter user Will Poundstone said in the T-shirt model discussion: "You try finding a person of colour willing to model a Trump shirt."
Donald Trump's most controversial quotes
Donald Trump's most controversial quotes
1/14 On Isis:
"Some of the candidates, they went in and didn’t know the air conditioner didn’t work and sweated like dogs, and they didn’t know the room was too big because they didn’t have anybody there. How are they going to beat ISIS?"
2/14 On immigration:
"I will build a great wall — and nobody builds walls better than me, believe me —and I’ll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words."
3/14 On Free Trade:
"Free trade is terrible. Free trade can be wonderful if you have smart people. But we have stupid people."
PAUL J. RICHARDS | AFP | Getty Images
4/14 On Mexicans:
"When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems. They’re bringing drugs. They’re bringing crime. They’re rapists."
5/14 On China:
"I just sold an apartment for $15 million to somebody from China. Am I supposed to dislike them?... I love China. The biggest bank in the world is from China. You know where their United States headquarters is located? In this building, in Trump Tower."
6/14 On work:
"If you're interested in 'balancing' work and pleasure, stop trying to balance them. Instead make your work more pleasurable."
7/14 On success:
"What separates the winners from the losers is how a person reacts to each new twist of fate."
8/14 On life:
"Everything in life is luck."
9/14 On ambition:
"You have to think anyway, so why not think big?"
10/14 On his opponents:
"Bush is totally in favour of Common Core. I don't see how he can possibly get the nomination. He's weak on immigration. He's in favour of Common Core. How the hell can you vote for this guy? You just can't do it."
11/14 On Obamacare:
"You have to be hit by a tractor, literally, a tractor, to use it, because the deductibles are so high. It's virtually useless. And remember the $5 billion web site?... I have so many web sites, I have them all over the place. I hire people, they do a web site. It costs me $3."
12/14 On Barack Obama:
"Obama is going to be out playing golf. He might be on one of my courses. I would invite him. I have the best courses in the world. I have one right next to the White House."
13/14 On himself:
"Love him or hate him, Trump is a man who is certain about what he wants and sets out to get it, no holds barred. Women find his power almost as much of a turn-on as his money."
14/14 On America:
"The American Dream is dead. But if I get elected president I will bring it back bigger and better and stronger than ever before and we will make America great again."
The grey T-shirt featured the 69-year-old's slogan: "Trump - Make America Great Again."
Its similarity to a picture on JCG Apparel's site was first tweeted by Eric Ming, digital director for Democrat senator candidate Donna Edwards, who said: "So it appears Donald Trump's campaign photshopped their model to be brown."
Several people also commented on the unnatural shade of skin tone used in the image, likening it to Mr Trump's own orange spray-tan appearance.
"It's not even a good Photoshop, too. The brown skin is so flat and featureless, barely any shadows," said Twitter user Haru Bell.
The image has since been taken down from the Republican front-runners apparel site.