A woman purporting to be the long-lost daughter of a late Long Island developer is laying claim to his $94 million fortune.

Ashley Mengoni, 31, says she is the child of Fred Mengoni, whose portfolio includes at least six rental apartment buildings on the Upper East Side, a Manhattan home and the well- known “White House” in East Hampton, a stunningly rebuilt mid-18th century Colonial on Woods Lane.

The young woman says she was a product of Mengoni’s brief 1986 marriage to Christine Foisy.

But Fred Mengoni’s longtime lawyer, the executor of his estate, denies it.

“Fred Mengoni told me that he married Christine Foisy in 1986 after she told him that she was pregnant. After the child was born . . . she admitted to Fred Mengoni that he was not the father,” attorney Charles Smalls wrote in recently filed Manhattan Supreme Court papers.

Smalls went to court to unseal the couple’s divorce record so he could investigate Ashley’s claim, but hadn’t had the chance to review the file when reached by The Post.

Ashley Mengoni couldn’t be reached.