*E! News is quoting “a source close to Whitney Houston” who is denying the singer was drunk or high during an altercation on a Delta Airlines flight to Atlanta.

As reported, the singer lashed out at a flight attendant after being told to buckle her seat belt. The news sparked rumors that Houston’s struggle with drugs and drink had reared its ugly head, but her camp says that was not the case.

“She was not drunk or on drugs, she is in the middle of filming a movie and flew across country to attend a charity event and return to filming. She was exhausted,” the source told E! News.

Houston reportedly refused to buckle up, leaving a flight attendant to fasten the seatbelt herself. Delta Airlines have announced they are looking into the situation, but claim they “cannot comment on passenger or itinerary information.”

Houston, who has a history of drug use, voluntarily checked herself into rehabilitation for drug and alcohol issues in May 2011. Another source close to the singer has told TMZ.com that the incident was an “overreaction,” saying “she’s still 100% sober and was on the way to Detroit for her first day of shooting a new movie.”

Whitney is currently shooting a remake of the 1976 film “Sparkle,” with Jordin Sparks and Mike Epps.