Strapped for cash, Mayor Bill de Blasio turned to a state political account he controls to buy plane tickets, pay rent and purchase digital advertisements for his nascent presidential campaign — potentially violating campaign finance regulations, campaign finance experts told The Post.

De Blasio’s presidential campaign disclosed it owes his NY Fairness PAC $52,852 — a tally that includes purchases made after Hizzoner officially announced his run, his staff confirmed.

The only problem: Federal law bars state groups — like de Blasio’s — from contributing more than $2,800 in cash, loans or purchases to a federal campaign during the primary election.

Purchases made “in cooperation, consultation or concert with, or at the request or suggestion of, a candidate’s campaign” are considered donations and count toward fundraising limits, according to Federal Election Commission guidelines.

De Blasio’s presidential campaign acknowledged in its FEC report that NY Fairness PAC spent those tens of thousands of dollars on its behalf to pay for campaign “travel expenses, digital advertising, [and] rent.”

NY Fairness PAC’s purchases for Hizzoner’s campaign included:

$40,000 in digital media consulting services purchased on May 15, the day before de Blasio’s launch;

$8,562 for “launch weekend travel,” including $3,970.70 in plane tickets bought on United Airlines, American Airlines and JetBlue Airways on May 16 and May 17;

$4,200 for rent at The Yard, the Brooklyn coworking space where de Blasio’s campaign is headquartered, which was paid in June.

However, the campaign booked the PAC’s spending as a debt, not as a contribution — a legal maneuver that stunned lawyers, campaign finance experts and political consultants.

“It appears de Blasio’s state PAC spending is in excess of federal limits,” said Tyler Cole, a top lawyer at Issue One, a Washington, DC, watchdog group that focuses on campaign finance reform. “Federal candidates must run their campaigns out of federally regulated committees — the law is only meaningful if they abide by the federal limits.”

He added: “You can’t allow candidates to use state committees to do an end-run around the law.”

The maneuver of listing state PAC expenditures as a campaign debt for a federal campaign instead of a donation stunned one Democratic strategist.

The donation limit end-run was “among the most creative ways to circumvent election laws that I’ve ever seen,” the source said.

“If it’s not a violation of the letter of the law, it’s certainly a violation of the spirit of the law,” the person added.

Beyond the nearly $53,000 debt disclosed to the FEC, The Post identified another $27,609 in NY Fairness PAC expenditures made on or after de Blasio’s May 16 announcement — including $9,130 for “digital services” from Trilogy Interactive.

De Blasio’s campaign claimed that spending was not related to the campaign.

All told, NY Fairness PAC reported spending $335,780 between Jan. 12 and July 11, the state filing shows.

“De Blasio continues to push the outer bounds of campaign finance law,” said Alex Camarda, a campaign finance monitor with the government watchdog group Reinvent Albany. “Spending on his presidential campaign should be done by his presidential campaign committee. Period.”

De Blasio claimed his campaign is following the law.

“We have complied with all of those regulations,” said campaign spokeswoman Jaclyn Rothenberg. “NYS law does not preclude a NYS PAC from spending in elections other than NYS elections.”

The NY Fairness PAC controversy is the latest ethics headache for de Blasio, who battled a string of campaign fundraising scandals during his first term.

Hizzoner narrowly avoided indictment in 2017 for trading favors with donors to his first 2013 mayoral campaign, his 2014 failed campaign to win control of the state Senate and to a nonprofit controlled by his allies, the Campaign for One New York.

Subsequently, a Department of Investigation report found Blasio’s CONY fundraising violated city ethics rules.

Additional reporting by Bernadette Hogan and Bruce Golding