Heather Mills ''appeared humiliated'' when her false leg was searched at Heathrow Airport, in London, after she set off a security alarm.
Heather Mills was ordered to have her false leg searched for explosives.
The model-and-charity campaigner - who lost the lower part of her left leg after being hit by a police motorcycle in 1993 - sparked a security alert at London's Heathrow Airport after her false limb triggered alarms as she passed through checks on her way to a departure lounge for her flight to the US.
An onlooker said: "Heather was flabbergasted. There was a brief impasse but she said nothing, just staring in disbelief.
"She quietly went and sat down shaking her head, and pulled up her trouser leg for an official to hold up her false limb and swab it.
"Heather looked furious but bit her tongue. She appeared humiliated at having her prosthetic leg highlighted in front of other passengers."
Airport officials insisted the swab was standard procedure.
A spokesperson for Heathrow owners BAA said: "She was swabbed because something set off the alarm in the metal detector archway.
"Staff could not see inside the leg so it was swabbed instead. This would be the same Protocol as if a passenger had a broken arm or leg."
Following her humiliating ordeal, Heather's experience worsened when she was refused access to the exclusive Concorde Lounge, which is reserved for first class passengers and guests and gives customers easy access to the flight gate.
After a row with receptionists - during which the 42-year-old star was apparently heard pleading "please let me through, I've had a bad day" - she was eventually allowed through.
Her spokesperson told the Daily Mirror newspaper: "She was told she could use the special BA door to the Concorde Lounge. But for whatever reason the guy on the door did not have the list with her name on. Their staff did not have the correct information.
"She was finally allowed to use the door to the Concorde Lounge to access another BA lounge because otherwise it would have meant a long walk around the terminal building."