The singer had been booked tickets on the flight by X Factor bosses, but was angry when she discovered she was not placed in first-class seating.
She was allegedly told at the airport that she was not allowed a free upgrade, and had to pay £3,500 to do so.
"Nicole was fuming," an insider told The Sun.
"She always flies first-class but she was amazed to find that she had been booked into economy. The X Factor books all of her flights — but she hadn't expected this.
"Nicole spent 20 minutes trying to get BA to upgrade her but in the end she had to put her hand in her pocket.
"There were a few mutterings about Simon Cowell being a tightwad."
Nicole Scherzinger was said to have broken down in tears following an emotional performance at Boot Camp last week.
Watch the video for Nicole Scherzinger's 'Don't Hold Your Breath' below: