A prominent Manhattan lawyer who has represented thousands of ailing 9/11 responders and survivors — and reaped a fortune in legal fees — was bilked out of $6.6 million by “art adviser to the stars” Lisa Schiff, a new lawsuit claims. 

Michael Barasch and his wife, real-estate heiress Candace Carmel Barasch, accuse Schiff of spending the millions they forked over on her own “lavish lifestyle” and to boost her alleged Ponzi scheme.

The couple gave more than $6.6 million to Schiff “for what they believed were purchases of artwork,” says the suit, filed this week in Manhattan Supreme Court.

“It now appears that much of the funds…was used instead to fund Schiff’s lavish lifestyle, cover debts owed to other clients, or to consummate art purchases for other clients,” the suit says.

Barasch told The Post the case is under criminal investigation by both the state Attorney General and the US Attorney’s office.

“My wife has been a patron of the arts for over 25 years,” he said. “She is passionate about helping young emerging artists, galleries, and museums. This fraud touched many, dozens of whom are now seeking justice.”

Barasch is a managing partner at Barasch & McGarry, which boasts it has represented 25,000 people “in the 9/11 community,” and collected $3 billion for victims and their families from the federal Victim Compensation Fund.

With the VCF limiting lawyer payments to 10 percent of awards, the firm has collected an estimated $300 million in fees. 

Schiff, whose clients included Leonardo DiCaprio, filed for bankruptcy on May 15, court records show.

Her lawyer, John Cahill, did not immediately return a request for comment.