"The small sachet tumbled out of the 20-year-old supermodel’s handbag and on to the floor as she searched for her keys...Cara swiftly covered the packet with her foot, then her handbag before snatching it up," reports UK tabloid The Sun.
The Sun also has a photo of Delevingne dropping the bag.
The 20-year-old walked in the Victoria's Secret runway show this year, modeling the PINK line for teens. She's also appeared in campaigns for H&M.
H&M is reportedly investigating the incident, according to The Daily Mail. The brand dropped Kate Moss after she was photographed allegedly snorting cocaine in 2005.
But Delevingne's career could suffer even more because of her influence on teenagers, reports Hayley Phelan at Fashionista.
"Case in point: this month she covers Miss Vogue, Vogue UK’s answer to Teen Vogue," Phelan writes. "At the time of the cover release, Vogue UK EIC Alexandra Shulman described Delevingne as 'Miss Vogue made physical' with a 'maverick sense of style and fun.'"
Delevingne has yet to respond to the incident.