Restaurateur Harendra Singh has admitted to bribing former Nassau County Executive Ed Mangano and former Oyster Bay Town Supervisor John Venditto, according to newly unsealed court documents. 

News 12 learned that Singh secretly pleaded guilty in October 2016, but his words were hidden from public view until the documents were unsealed Wednesday. His guilty plea also names an unnamed New York City official.

Those documents show that Singh admitted offering and giving Mangano and Venditto bribes and kickbacks in exchange for them taking official action in his favor on an as-needed basis. The actions happened between January 2010 and February 2015, according to the documents.

"This is extraordinary that we would find out in discovery papers that we have another principle in the case pleading guilty to these charges," says Joye Brown, a Newsday columnist. 

The Manganos and Venditto have all pleaded not guilty. They are scheduled to go on trial on their own federal corruption charges in March.

Singh said some of the gifts he gave Mangano included a massage chair, an office chair and wood flooring to be installed in the master bedroom of the Manganos' home. Singh said he paid for a watch worth approximately $7,000 for one of Mangano's sons.

In addition, Singh admitted to paying for trips for Mangano and his family. Singh said he also provided a no-show job to Linda Mangano from 2010 through 2014 -- and that he paid her approximately $450,000. Singh said he hired Linda Mangano at the request of Ed Mangano, and his purpose in hiring her was to influence the county executive.

Singh also said he gave Venditto, his family and other Oyster Bay officials free meals and significantly discounted rates for events at his restaurants and catering halls, free use of conference rooms and free limousine service.

Singh said both the town and county awarded contracts to him in return for the gifts and bribes. Singh also said the town guaranteed loans to Singh's companies worth in excess of $20 million, collectively.

According to the plea transcript, Singh agreed to be a key witness in the corruption case on Long Island against Mangano, his wife and Venditto.

Singh has waived his right to appeal. The plea deal did not specify a promised sentence.

"The release of this plea reveals what we knew -- facing decades in prison for his own vast and hidden criminality Singh struck a deal," Kevin J. Keating, an attorney for Mangano, said in a statement. 

Venditto's lawyer did not immediately respond to a News 12 Long Island request for comment.