Suffolk County District Attorney Thomas Spota said Monday he won’t appear before county legislators later this week because of a U.S. Attorney investigation into his office.

“As you are aware, there is an ongoing investigation by the United State Attorney’s Office into matters relating to your request,” Spota wrote to Public Safety Chairwoman Kate Browning (WFP-Shirley).

He also cited a request by Suffolk County Executive Steve Bellone that Governor Andrew M. Cuomo investigate Spota.

“While these matters are pending, and for reasons described below, I cannot answer questions related to them at this time,”

Spota wrote.

He also said that under state law he could not talk about grand jury proceedings.

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Browning last week wrote that Legis. William Lindsay III (D-Bohemia) had requested Spota to appear at Thursday’s public safety committee meeting in Hauppauge. Browning cited disclosures in Newsday that Spota’s office failed to prosecute possible criminal activity uncovered in wiretaps, along with other cases.

Newsday reported Saturday that federal investigators are probing whether Spota and one of his chief assistants took part in a cover-up of an assault by former Suffolk Police Chief of Department James Burke of a burglary suspect, according to sources.

Browning and Lindsay didn’t immediately respond to a request for comment.

Spota, in his letter, attached his office’s responses to Newsday stories and answers in January to a New York Times reporter’s questions for a story he was preparing.

Spota defended his ofice.

“While the persistent attacks on my integrity and that of my staff have been distressing and distracting, the important work of the District Attorney’s office continues,” he said.

Bellone, a Democrat, Sheriff Vincent DeMarco, a Conservative, and five of six Republican county legislators have called on Spota to resign.