Wade Robson's claims come eight years after he defended Jackson from molestation claims from other children, and denied he was a victim.
The Jacksons are to bring their reunion tour to the UK with five newly-announced dates next year.
Singer Diana Ross made a failed bid to try and delay the appointment of a guardian to Michael Jackson's three children.
Michael Jackson's mother Katherine and nephew TJ will share guardianship of the late singer's three children, Los Angeles Superior Court Judge Mitchell Beckloff said.
Tito Jackson's son has been appointed by a judge as a temporary guardian of Michael Jackson's children, according to the Associated Press.
The appointment comes after their guardian, their grandmother Katherine Jackson, was reported missing by a relative before being located safely with other family members in Arizona.
The judge suspended her guardianship as she is in a different state and had not spoken to the children in years.
Police are investigating a family disturbance and possible assault at the home of Michael Jackson's mother.
Los Angeles Sheriff spokesman Steve Whitmore said no-one was arrested after deputies were called to Katherine Jackson's home around 1.10pm local time yesterday.
He said deputies concluded there had been a physical altercation between two people and the case remains under investigation, as a possible battery.
The incident is the latest drama for the Jackson family.
Authorities believe Katherine Jackson, the mother of Michael Jackson and the guardian of the pop legend's three children, is safe in Arizona with family members after she was reported missing.
Katherine Jackson is reportedly with her daughter Rebbie in Arizona and following a doctor's orders to rest.