Joanne Catherall, one third of the Don't You Want Me hitmakers, claims she was refused entry to the business class lounge at Melbourne Airport because of her footwear.
The 55-year-old star was travelling to Sydney for a gig as part of the band's Australian tour and took to Twitter to blast being blocked.
'Denied access @Qantas business class lounge in @Melair Melbourne Airport apparently Ugg (Australia) Boots are deemed sleepwear by the lady working there although no problem in any of the other lounges so far,' she wrote.
But Qantas hit back a few moments later tweeting: "Hi Joanne, we endeavour to remain consistent and uphold our Lounge's dress guidelines to all our guests,' adding a link to the company's sartorial code.
The guideline explained that alongside 'thongs' (flip-flops) and unclean clothing, Ugg boots were deemed unacceptable.
But the singer refused to let the matter drop and responded: "Why would an @UGG boot I wear outdoors in all weathers be classed as sleepwear in @Qantas lounge but nowhere else that I have ever been on this earth?"
In a curt response, Qantas simply wrote: 'Hi Joanne, we don't accept them in our lounges as you can see on the dress-guidelines'.
In its dress guide, the airline tells passengers its 'lounges are a place where you can sit back and relax before your flight'.
But it adds: 'To ensure an enjoyable experience when you're visiting our domestic Qantas Clubs and Business Lounges in Adelaide, Brisbane, Canberra, Melbourne, Perth and Sydney, we ask that you follow our smart casual dress guidelines.
'Our team will decline entry if some items of clothing are too casual or inappropriate. This includes, but is not limited to:
Thongs (flip-flops) and bare feet
Head to toe gym wear
Beachwear (including board shorts)
Sleepwear (including UGG Boots and slippers)
Clothing featuring offensive images or slogans
Revealing, unclean or torn clothing.'
In a statement to the Independent about the incident, Qantas said: 'We completely understand that no one likes being declined at the door but we've always had smart casual dress standards for our lounges, which are similar for those in place for most clubs and restaurants.
'Over the past couple of years we have had clear feedback from lounge members that they wanted these existing guidelines to be applied more rigorously.'
Catherall, along with fellow female vocalist Susan Sulley has been part of the Sheffield band since 1980.
They were famously recruited by lead singer Phil Oakey when the pair were discovered in the city's Crazy Daisy Nightclub.
At short notice she and Sulley were invited to join the band's European tour that was in crisis after the original group had split. The pair then joined Oakey in forming a new and commercially successful line-up of The Human League, in turn making an international pop star of Catherall.