NEW YORK (REUTERS) - Lawyer Michael Avenatti, who represented adult film star Stormy Daniels in her legal battles against US President Donald Trump, was arrested on Monday (March 25) and charged with trying to extort more than US$20 million (S$27 million) from Nike Inc, federal prosecutors said.

The US Attorney's offices in New York and Los Angeles separately filed charges against Avenatti, with the California case accusing him of embezzling a client's money to cover his own debts, as well as using phony tax returns to obtain millions of dollars in loans from a bank.

New York prosecutors said Avenatti and an unnamed co-conspirator met with Nike's attorneys on March 19 and tried to extort the company into paying them between US$15 million and US$25 million and an additional US$1.5 million to a client of Avenatti's by threatening to make public allegations against the company.

Prosecutors said Avenatti also offered to accept a US$22.5 million payment to resolve any claims the client might have, and to "buy Avenatti's silence." In a March 20 follow-up call with Nike's lawyers, Avenatti said that if his demands were not met, "I'll go take ten billion dollars off your client's market cap ... I'm not f***ing around," according to the complaint.

The charges were revealed shortly after Avenatti said on Twitter that he would hold a news conference on Tuesday to reveal "a major high school/college basketball scandal" that reached "the highest levels of Nike."

Avenatti gained international fame for representing Daniels, the pornstar whom Trump is accused of paying off shortly before the 2016 election to keep quiet about an alleged affair. Trump has denied having an affair with Daniels.

Nike did not immediately respond to a request for comment.