Wayne Newton -- Accused of Creepy Old Man Kisses

Wayne Newton is a sexually deviant kiss fiend -- this according to a new lawsuit filed against Mr. Las Vegas.

70-year-old Wayne is being sued by a former business partner, who claims he invested millions to turn Newton's Vegas mansion into a museum -- and Newton torpedoed the project.

According to the lawsuit, Newton and his family continually interfered with the development plans -- refusing to vacate the mansion to allow construction to take place, failing to remove his horses and "vicious" dogs from the property, and refusing to turn over memorabilia crucial to the operation of the would-be museum.

But the shocking part ... Newton's ex-biz partner claims the Vegas icon was "so sexually reprehensible and intimidating" to a young female worker, the girl not only quit ... she threatened to sue.

According to the lawsuit, the girl claims Newton "engaged in obnoxious sexual behavior" -- forcing her to withstand constant "wet, sloppy, and disgusting" kisses that were "clearly of a sexual nature."

According to the lawsuit, the alleged affronts left the girl feeling violated -- "She had to brace herself every time she saw him for this inevitable assault."