Cory Booker pocketed “confidential” annual payouts from his former law firm while serving as Newark mayor.

Booker, the front-runner in New Jersey’s Senate race, received five checks from the Trenk DiPasquale law firm from 2007 until 2011. During that time, the firm raked in more than $2 million in fees from local agencies over which Booker has influence.

“This was a settlement buyout for my interest in the firm,” the mayor told The Post at a campaign stop in Jersey City yesterday. “I had an equity stake, and we had a negotiated settlement.”

Booker worked at the West Orange firm for five years, leaving in 2006 when he was elected Newark’s mayor to avoid “the appearance of impropriety.”

He refused to answer how much he received in the five years after leaving.

“It’s all been disclosed for the last seven years,” Booker said.

Not quite. Booker’s state financial disclosures from 2006 to 2011 list two sources of income — the city of Newark and the law firm. The forms mandate reporting of income over $2,000 a year, but do not require an exact sum or range.

Booker’s closed lips on the earnings fly in the face of his public stances. In 2002, he released his tax returns during his unsuccessful race against incumbent Mayor Sharpe James, and ripped James for not doing the same.

The returns “provide the only clues as to how many deals the mayor is involved in . . . and the only record of the money he’s making on the side,” Booker said at the time.

When The Post asked Friday for Booker’s recent returns, his campaign refused to turn them over.

“We will release his tax returns,” said campaign spokesman Kevin Griffis, without indicating when.

Booker and the Trenk DiPasquale firm cited a “confidential” separation agreement. The firm added, “Since Mr. Booker left the firm in 2006, he has provided no services or work to the firm.”

Booker did not list Trenk DiPasquale as a source of income on the financial-disclosure report he filed as a Senate candidate in May. One part asks for a listing of compensation of more than $5,000 paid by one source for services provided from 2011 to 2013.

Griffis claimed Booker did not have to list his 2011 payment from the law firm because “it was not compensation for services rendered. It was a return of equity.”

Booker quit the firm Oct. 31, 2006.

Since 2007, the firm has raked in at least $1,287,639 in legal fees from Newark’s Housing Authority, $554,663 from a local wastewater agency, and $212,318 from the Newark Watershed, records show.

Soon after becoming mayor, Booker appointed Modia Butler — the head of a nonprofit that he organized, Newark Now — to the authority board. Butler later became board chairman.

Elnardo Webster, a former law partner at the firm — and longtime Booker friend and political adviser — serves as the Watershed’s attorney. Booker served on the Watershed’s board.

In 2008, a company run by relatives of another ex-law partner, Richard Trenk, bought a 5-acre plot from the authority to build a commercial heliplex, The Star-Ledger reported. While Trenk had a $500,000 contract with the authority to work on redevelopment issues, the agency said the lawyer wasn’t involved in the deal with his uncle and two cousins.

State Sen. Ron Rice, Booker’s opponent in the 2006 mayoral race, questioned the relationship between Booker and the firm.

“Booker did nothing but bring in business to that law firm. He’s bringing it indirectly to them now,” Rice charged.

Booker collects a $174,496 annual mayoral salary, made $1.3 million in speaking fees over five years, and holds a $1- to $5-million stake in his Internet startup, Waywire, he reported on his Senate disclosure form.

Cory Booker

* Became mayor of Newark on July 1, 2006.

* Partner in Trenk DiPasquale law firm from 2002 to 2006, when he resigned to avoid an “appearance of impropriety.”

* From 2006 to 2011, he collected annual payouts of more than $2,000 each as part of a “confidential separation agreement” with the firm.

* Firm raked in $2million in fees from the Newark Housing Authority, a public wastewater-treatment agency, and the Newark Watershed.

With Lia Eustachewich