A federal corruption probe into New York City Police Department officials taking cash for favors from two businessmen has spread to Mayor Bill de Blasio and his fundraising efforts, according to published reports.

The businessmen, Jona Rechnitz and Jeremy Reichberg, and their influence on New York City government has been the subject of an investigation “for some time,” according to The New York Times, citing several people briefed on the matter.

Federal investigators interviewed nearly 20 NYPD officials and have since focused on de Blasio’s fundraising, as first reported Friday night by WCBS-TV.

Rechnitz, owner of JSR Capital LLC, a real estate investment, development and management company that owns buildings in Manhattan and Brooklyn, raised about $45,000 for de Blasio, while he and his wife each contributed the maximum allowed — $4,950 — to his 2013 campaign, according to the Times.

Rechnitz and Reichberg were on a committee that planned de Blasio’s 2014 inaugural party. Reichberg also hosted a fundraiser in 2014 for the Campaign for One New York, a nonprofit created by de Blasio advisers in support of his progressive movement.

The businessmen could not be reached for comment Saturday.

De Blasio began closing down the group last month after it was bashed by watchdog groups as a “shadow government” of lobbyists at City Hall.

While it was not immediately clear what aspects of de Blasio’s fund-raising is under examination or how it relates to the two businessmen, de Blasio’s campaign has said it will return the $9,900 in contributions to Rechnitz and his wife.

“We are fully confident that the campaign has conducted itself legally and appropriately at all times,” campaign spokesman Dan Levitan said Saturday in a statement.

The federal investigation has garnered heavy media attention in the past several days with four senior police department officials — including three deputy chiefs and a deputy inspector — reassigned to desk duties as a result of the investigation.

Monica Klein, a spokeswoman for de Blasio, could not be immediately reached.

“The mayor is fully supportive of these investigations to learn the truth,” Klein said in a statement to the Times.

With Matthew Chayes