The indicted restaurateur Harendra Singh is a “sleazy guy” whom Bill de Blasio should be “ashamed” of being involved with, GOP mayoral challenger Nicole Malliotakis said Thursday.

Standing outside Singh’s shuttered Water’s Edge restaurant in Queens for which Singh had enlisted de Blasio to settle a rent dispute with the city, Malliotakis said the mayor’s favors for Singh are “a symbol of all that is wrong in Bill de Blasio’s New York.”

“This is a sleazy guy, and he is now indicted in corruption scandals for bribery in Long Island. This mayor — why he would put this individual on various boards and committees is beyond me,” said Malliotakis, an assemblywoman from Staten Island.

Singh, a longtime donor to de Blasio, held fundraisers for the mayor, including at Water’s Edge, and was rewarded with honors such as an appointment to his inaugural committee. Top officials in de Blasio’s administration — including his first deputy’s chief of staff, his counsel and his political fixer — intervened in Singh’s dispute with the city, which owns the restaurant’s land, over more than $1 million in owed rent and other fees. An audit had found that Singh had been underpaying rent.

“This mayor all along had been rewarding him simply because he was a donor and that is why this mayor is a failure,” Malliotakis said.

Singh was arrested and charged in 2015 by the FBI, accused of bribing a now-former Oyster Bay Town official, tax fraud and lying to federal agents. He’s also at the center of a case involving Nassau County Executive Edward Mangano, who pleaded not guilty last fall to federal charges that he got bribes and kickbacks from Singh in exchange for county work.

The Manhattan U.S. attorney’s office in March dropped an investigation into de Blasio’s campaign finances, including those with Singh, finding insufficient evidence to charge anyone. But the office said his team fielded donations from favor-seekers “after which the mayor made or directed inquires to relevant city agencies on behalf of these donors.”

Malliotakis said she “might” rehire Ricardo Morales, a city official who said he was fired by the de Blasio administration after voicing concern that Singh was getting special treatment because of being a donor.

“It appears that somebody was wrongfully fired for being honest and not doing the mayor’s bidding,” Malliotakis said.

Morales, a former deputy commissioner, has filed a notice of claim that he plans to sue the city for at least $5 million. He says he was “unlawfully” let go because he raised concerns about Singh and preferential treatment by the mayor.