Donald Trump campaign mistakenly tweets star-spangled Nazis

Republican presidential candidate Donald Trump's campaign on Tuesday inadvertently tweeted a promotional photo featuring what appeared to be Nazi German soldiers superimposed on the US flag alongside the controversial real estate magnate's face.

The gaffe, which Trump's campaign blamed on an intern, was the latest setback for the TV show host who lost business deals with Univision, NBC and NASCAR after making comments about Mexican rapists immigrating to the United States.

The tweeted picture also shows the White House and a $100 bill and the slogan, "We need real leadership. We need results. Let's put the US back into business!"

"A young intern created and posted the image and did not see the very faded figures within the flag of the stock photo. The intern apologised and immediately deleted the tweet," Trump's campaign said.

The four soldiers pictured seemed to be actors wearing the uniforms of the notorious SS force, Twitter users said.

On Monday, an aide to Trump said that the FBI is investigating threatening tweets to him that were purported to have originated from Joaquin Guzman, aka El Chapo the Mexican drug lord who escaped from prison on Saturday.

Read: Watch: Here's how Mexico's drug lord Joaquin Guzman escaped prison