Justin Bieber has been accused of humiliating a female fan in a gym by jeering her during her workout.

The 'As Long As You Love Me' singer - who was dumped by his girlfriend of two years, Selena Gomez, earlier this month - allegedly proceeded to mock NC radio host Colette Harrington and possibly spat blue Gatorade into her water bottle after she asked him for a photograph in the Ritz-Carlton Hotel gym in North Carolina on Tuesday (22.01.13).

Colette told gossip website TMZ.com that the 18-year-old Canadian popstar, who had a concert in the city on Tuesday night, declined to pose for the picture but then started imitating her after she continued to lift weights.

She said: ''I always count out loud my reps. Then Justin starts imitating me and whenever I'd get to 20 he and his buddy would say 'Shut the F**k up.'''

Colette - who has since filed a complaint with the hotel about the alleged incident - claims she also noticed a spitball of blue Gatorade in her water bottle after accidentally taking a drink.

She said: ''I did not look at my water bottle before taking a drink.''

Justin Bieber and the Ritz-Carlton declined to comment on the story but the woman has revealed she plans to sell the water bottle with the spit on eBay in a bid to make some money for a local charity, where she volunteers.