(Adds details from indictment, byline)
By Jonathan Stempel
NEW YORK, May 22 (Reuters) - Michael Avenatti's legal troubles escalated on Wednesday as federal prosecutors announced new criminal charges accusing the lawyer and prominent critic of U.S. President Donald Trump of stealing from porn star Stormy Daniels and extorting Nike Inc.
Prosecutors accused Avenatti, 48, of stealing about $300,000 from Daniels, about half of which has not been repaid, after helping his former client secure a book contract.
They also said he has been indicted on previously announced charges that he tried to blackmail Nike out of more than $20 million by threatening to expose what he called the athletic wear company's improper payments to recruits for college basketball teams it sponsored.
The charges were announced by U.S. Attorney Geoffrey Berman in Manhattan.
Avenatti also faces dozens of charges in California, where prosecutors on April 11 accused him of stealing millions of dollars from clients to pay for personal and business expenses, and lying to the Internal Revenue Service and a Mississippi bank about his finances.
If convicted on all charges, Avenatti could face several hundred years in prison.
Avenatti has maintained his innocence, and said the earlier prosecutions were a means to punish him for representing Daniels and being a Trump critic.
"I look forward to a jury hearing all of the evidence and passing judgment on my conduct," he wrote on Twitter after Wednesday's charges were announced.
"At no time was any money misappropriated or mishandled," he added. "I will be fully exonerated once the relevant emails, contracts, text messages, and documents are presented."
Lawyers for Avenatti did not immediately respond to requests for comment.
Avenatti represented Daniels in lawsuits arising from what she called her 2006 sexual relationship with Trump, and a $130,000 hush money payment from former Trump lawyer Michael Cohen shortly before the 2016 presidential election.
According to court papers, Avenatti diverted a significant portion of Daniels' $800,000 book advance after sending her literary agent an unauthorized letter purporting to contain her signature, and directing that money be sent to his bank account.
Prosecutors said Avenatti spent some diverted money on monthly lease payments for a Ferrari, hotels, airfare, restaurant meals, car service and business expenses.
When Daniels asked why she had not received a $148,750 installment payment, Avenatti lied by telling her he had yet to receive it from the publisher, according to court papers.
Prosecutors said he later paid Daniels with money obtained from another source, so she would not realize it had been diverted.
Daniels, whose real name is Stephanie Clifford, is identified in court papers as "Victim-1." A person familiar with the matter who was not authorized to speak publicly confirmed her identity.
The charges related to Daniels include one count of wire fraud and one count of aggravated identity theft, and carry a maximum combined penalty of 22 years in prison.
Trump has denied having had sex with Daniels. Cohen is two weeks into his three-year prison term after pleading guilty to campaign finance violations, including the hush money payment.
Avenatti, who flirted last year with a 2020 White House run, became a familiar face on cable news channels as his stature grew, but has had a lower profile since being indicted.
Reporting by Jonathan Stempel in New York; Editing by Lisa Shumaker