The ad shows people rushing towards a border fence as the narrator says he "will stop illegal immigration" from Mexico but the footage used is of a Spanish enclave in Morocco.
A prominent fact-checking organisation Politifact, citing footage from May 2014 on an Italian television network, wrote yesterday that migrants shown were not crossing into Arizona or Texas -- but into the Spanish enclave of Melilla on the African coast. The footage shows Moroccans fleeing.
"Trump's television ad purports to show Mexicans swarming over 'our southern border.' However, the footage used to support this point actually shows African migrants streaming over a border fence between Morocco and the Spanish enclave of Melilla, more than 5,000 miles away," PolitiFact said in its ruling on the ad.
Trump's campaign, in a statement to Fox News, said the use of the footage was "intentional and selected to demonstrate the severe impact of an open border and the very real threat Americans face if we do not immediately build a wall and stop illegal immigration."
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Trump campaign manager Corey Lewandowski told NBC News, "It's not the Mexican border but that's what our country is going to look like. This was 1,000 per cent on purpose."
Trump's much-awaited first TV ad features a promise that once he is at the helm he will "quickly cut" ISIS' head and "take their oil".
Trump's ad begins with a shot of President Obama and Hillary Clinton. Then comes a US battleship launching a cruise-missile strike. It moves swiftly through an explosive montage -- the suspects in the recent California terrorist attack, shadowy figures racing across the US-Mexico border and Islamic State militants.
Earlier, Trump had come under fire after responding to President Obama's Oval Office speech in December.
"Muslim Americans are our friends and our neighbours; our co-workers, our sports heroes - and, yes, they are our men and women in uniform," Obama said.
That prompted Trump to tweet the following: "Obama said in his speech that Muslims are our sports heroes. What sport is he talking about, and who? Is Obama profiling?"