The Rev. Al Sharpton may claim he wore a wire for the feds because he had been threatened by the mob — but a new report says he turned rat to save himself after a federal drug sting.

The FBI “flipped” the bombastic reverend after agents confronted him with a surveillance video showing him discussing cocaine with an ­undercover agent, The Smoking Gun Web site said Wednesday.

During that March 1983 conversation, Sharpton wore a cowboy-like hat that was garish even by the rabble-rousing preacher’s 1980s standards.

He later showed up at a Manhattan apartment for another meeting that June with the agent, who was posing as a “former South American druglord seeking to launder money through boxing promotions,” the report said.

Instead, Sharpton was met by G-men who were not undercover — and who showed him the “drug” video, the Web site said, citing a source familiar with Sharpton’s secret FBI file.

“The panicked reverend agreed — on the spot — to cooperate with federal agents,” The Smoking Gun said.

The Web site said that, at the FBI’s direction, Sharpton initially targeted boxing promoter Don King for undercover recording. King was the principal target of the FBI operation that netted the reverend in an operation called “Crown Royal,” The Smoking Gun said.

The FBI even gave Sharpton an undercover-snitch code name, CI-7, short for Confidential Informant #7.

The new claims fly in the face of Sharpton’s insistence Tuesday that he turned government informant in a heroic effort to stand up to mob threats.

“I was not and am not a rat,” he said.

“I know I was threatened [by mobbed-up entertainment figures]. I did what anybody would do that is respected . . . I cooperated,” he said.

“You had two options: Get killed by the mob . . . or get killed for trying to get them out of your community.”

After he turned snitch, Sharpton helped bust famous mob figures such as Vincent “Chin” Gigante, The Smoking Gun reported earlier this week.

He also reportedly recorded Genovese soldier “Joe Bana” Buonanno.

The FBI declined to comment, and a Sharpton spokes­woman wouldn’t say if he would authorize the release of his secret file to settle the matter.

Meanwhile, Sharpton held court Wednesday at his National Action Network’s annual convention amid the scandal.

Mayor Bill de Blasio cut a red ribbon to kick off the four-day event, which also drew city Comptroller Scott Stringer and state Comptroller Thomas DiNapoli to Sharpton’s side.

The White House said the Sharpton furor wouldn’t stop President Obama from delivering the NAN keynote address on Friday in Midtown.