The White House has defended US President Donald Trump after he aimed an offensive gesture at a heckler during his appearance at the Ford factory in Detroit on Tuesday.

Footage of the incident published by TMZ appears to show Trump responding to a man who shouted at him from afar.

The White House said, "A lunatic was wildly screaming expletives in a complete fit of rage, and the President gave an appropriate and unambiguous response."

The heckler has been suspended by Ford, the United Auto Workers union told CBS News, the BBC's US partner. Within 24 hours of the incident, two separate GoFundMe pages have raised nearly $700,000 (£521,000) for him from more than 27,000 donors.

A Ford spokesperson told CBS, "One of our core values is respect, and we don't condone anyone saying anything inappropriate like that within our facilities.

"When that happens, we have a process to deal with it, but we don't get into specific personnel matters."

According to the subtitles provided by TMZ, the heckler called Trump a "paedophile protector".

In the clip, which shows Trump from a distance, the president can be seen speaking back to the heckler, allegedly mouthing an expletive and using a middle-finger gesture.

A man named TJ Sabula, who spoke to The Washington Post, identified himself as the man who shouted. He said he had "no regrets" about what he did.

Sabula reportedly said he his remarks referred to Trump's handling of the Epstein files.

Trump has faced pressure for more transparency on what was uncovered by federal investigations into Jeffrey Epstein, the late convicted sex offender.

Trump signed a law that compelled the Department of Justice (DoJ) to release all the files that it held on Epstein by 19 December, although only a fraction of the files have so far been made public.

Trump was once friends with Epstein before they fell out, which Trump says was years before Epstein was first arrested. Trump has not been accused of any wrongdoing in connection with Epstein.

United Automotive Workers (UAW), the union that represents Sabula, defended his actions, saying: "He believes in freedom of speech, a principle we wholeheartedly embrace, and we stand with our membership in protecting their voice on the job."

Trump was in Detroit on Tuesday to give a speech to the Detroit Economic Club.

The president's public use of expletives has attracted headlines in the past - for example, when discussing the relationship between Iran and Israel last June.

His predecessor, Joe Biden, also caused controversy for uttering an expletive during a conversation with a worker during his 2020 campaign-trail visit to a Detroit factory, before he was elected president.