Rome's embattled mayor, Ignazio Marino, reportedly resigned Thursday amid accusations he expensed family dinners, claiming they were official business.

Newspapers have documented a half-dozen dinners where either the alleged guests or the restaurant itself disputed Marino's version of events. He promised Wednesday to pay the entire 20,000 euro ($22,600) credit card bill, including uncontested legitimate expenses, back to the cash-strapped city.

Italy's SkyTG24 and ANSA news agency cited a statement from Marino late Thursday in which he defended his administration and said it had rooted out corruption and mafia infiltration in city hall from the previous mayor. He said his resignation was not an admission of guilt and noted that Italian law allows resignations to be rescinded within 20 days.

Marino, a liver transplant surgeon who became a politician a decade ago, has denied wrongdoing.

Marino had been increasingly isolated by his own party, and saw his popularity plunge, following a series of scandals and corruption probes involving Rome's public administration, most of them concerning alleged wrongdoing under his predecessor's term.

But Marino has been responsible for some of his own undoing. Last year, he faced pressure to resign after he let parking fines pile up for his red Fiat Panda, which was repeatedly ticketed for being parked in the city center without a permit. Marino, who mostly gets around town on his bike, blamed careless aides for letting the permit expire.

Over the summer, Marino was harshly criticized for staying on vacation in the U.S. while Rome erupted in outrage over a Hollywood-style funeral for a purported organized crime boss that included a police escort. For many, it was a display of opulence at a time when the city's basic services like public transport and garbage pickup were being grossly neglected by strikes, mismanagement and cutbacks.

More recently, even the Vatican lost confidence in his ability to govern.

Pope Francis appeared visibly irked by Marino's reported suggestion that he had been asked by the Vatican to attend the pope's big final Mass in Philadelphia, the culmination of his recent U.S. tour. In a news conference coming home, Francis made clear that neither he nor the organizers of the church's Catholic family rally had invited him.

Subsequently, the Vatican official who co-sponsored the Philadelphia event was caught on a prank phone call disparaging Marino and questioning whether he could get Rome ready for the millions of pilgrims expected to come for Francis' Jubilee Year of Mercy, which begins on Dec. 8.

A clearly embarrassed Vatican later was forced to insist that relations with Italy were fine.

Marino was elected mayor in 2013, promising to bring order and function to Rome's chronically dysfunctional public administration. Some of his early moves endeared him to the public -- the bike, for example. But he also took some unpopular decisions, including closing a main thoroughfare through Rome's iconic Foro Imperiali to cars, further snarling the center's congested traffic.

He also had a cloud hanging over him concerning a previous expense account scandal.

Marino, who had worked as a surgeon and researcher at the University of Pittsburgh Medical Center, left the U.S. to pioneer a transplant hospital in Sicily that was affiliated with the U.S. center. But he abruptly resigned in 2002 as director of Sicily's ISMETT transplant center.

The U.S. institution said at the time that hospital auditors had found a pattern of "intentional duplicate" expense accounts submitted by Marino.

The Associated Press contributed to this report.