Donald Trump's former White House physician disputed on Friday a suggestion by the FBI director that shrapnel, not a bullet, could have caused the injury to the Republican presidential candidate's right ear during an assassination attempt in Butler, Pennsylvania on July 13.

The narrative that a bullet ripped through Trump's ear, and that he escaped death by just a quarter of an inch, has become a major element of the former president's White House campaign. Many of his supporters say the fact he survived was divine intervention and Trump mentions his brush with death in his speeches.

"I took a bullet for democracy," Trump told supporters at a rally in Grand Rapids, Michigan, on July 20.

Ronny Jackson, Trump's doctor when he was in the White House, released a statement a day after Trump criticized FBI Director Christopher Wray for telling U.S. lawmakers this week it was not clear whether Trump was hit by a bullet, or shrapnel or glass.

"There is absolutely no evidence that it was anything other than a bullet," wrote Jackson, a close Trump ally. "Director Wray is wrong and inappropriate to suggest anything else."

On Friday evening, several hours after Jackson's statement, the FBI said in a statement: "What struck former President Trump in the ear was a bullet, whether whole or fragmented into smaller pieces, fired from the deceased subject’s rifle."

Jackson, who said he served as a battlefield medic in Iraq and had treated many gunshot wounds in his career, has been monitoring Trump's wounded ear since the assassination attempt.

On Thursday, Trump took to his Truth Social social media account to blast Wray.

"No, it was, unfortunately, a bullet that hit my ear, and hit it hard. There was no glass, there was no shrapnel," Trump wrote, adding: "No wonder the once storied FBI has lost the confidence of America!"

Jason Miller, a Trump campaign spokesperson, told Reuters any claims that Trump was hit by something other than a bullet was "conspiracy bullshit."

Trump said on Friday that he plans to return to Butler to hold another rally.

He said the purpose of the return rally was to honor Corey Comperatore, the 50-year-old volunteer firefighter killed in the attack, and other Trump supporters injured by the gunman.

Trump did not say when the rally will take place, telling supporters: "Stay tuned."