Attorney Michael Avenatti, speaks outside court in New York. File photo: AP Photo/Julio Cortez.

Los Angeles - Michael Avenatti, the flamboyant lawyer who represented porn star Stormy Daniels in her legal battle with US President Donald Trump, has been indicted on charges of theft, fraud and tax evasion, authorities said Thursday. 

Prosecutors say Avenatti stole millions of dollars from his own clients and kept millions of dollars in employment taxes that his coffee company should have paid to the Internal Revenue Service.

The 36-count indictment by a federal grand jury exposes Avenatti to up to 333 years behind bars if convicted, Nick Hanna, US Attorney for the Central District of California, said.

"In the event of his conviction, we seek to have proceeds of Mr. Avenatti's fraudulent conduct forfeited to the government. Authorities seized a $5 million jet that Mr. Avenatti co-owned, a purchase he made from money allegedly stolen from a client," Hanna told a news briefing.

The charges he faces include tax fraud, bank fraud and bankruptcy fraud.

"The financial investigation conducted by the IRS details a man who allegedly failed to meet his obligations to the government, stole from his clients, and used his ill-gotten gains to support his racing team, the ownership of Tully’s coffee shops, and a private jet," said IRS Acting Special Agent in Charge Ryan Korner.

The wire fraud charges are related to the more than $12 million he received for his clients from lawsuit settlements and other negotiations. The indictment alleges that Avenatti stole millions of dollars from clients he represented in four matters.

"In each of the four cases of embezzlement alleged in the indictment, Avenatti received money on behalf of clients into client trust accounts, misappropriated the money, and lied to the clients about receiving the money or, in one case, claimed that the money had already been sent to the client," a Justice Department statement explained.

Avenatti, who has been released on a $300,000 bond, is to be arraigned April 29 in United States District Court in Santa Ana, California.

"I intend to fully fight all charges and plead NOT GUILTY," the attorney said on Twitter. 

"I look forward to the entire truth being known as opposed to a one-sided version meant to sideline me."

- Nike case -

Avenatti faces charges in a separate case in New York involving the sports apparel giant Nike.

According to that complaint, the celebrity attorney devised a scheme to extort millions of dollars from Nike by threatening to damage the company's reputation right before its quarterly earnings report and the start of the NCAA men's basketball tournament.

California-born Avenatti, 48, at one point entertained the possibility of running for president. He rose to fame after representing Daniels in her legal battles with Trump over hush money she received for an affair she allegedly had with Trump in 2006. 

He no longer represents Daniels.

In addition to Daniels, Avenatti's clients have included singer R Kelly, and Julie Swetnick, who said she witnessed sexually abusive behavior by Brett Kavanaugh, the US Supreme Court justice whose volatile confirmation process was marked by multiple accusations of sexual assault when he was in high school and college.