Ads for pairs of "plain functional buttoned adult pyjamas" promoted by multiple retailers began appearing on websites last week.

The adverts first garnered attention after multiple people reported seeing ones featuring the brand IVRose while reading a story on Elle.com. IVRose's Facebook page is managed by a Chinese firm called Shanghai Lishang Information Technology Co Ltd. Its contact details match those of another fast-fashion website, ChicMe, whose name features in an almost identical advert. Its website is owned by Alkmand Estate Ltd, which operates numerous clothing websites, all of which have been running the same or similar pyjama adverts.

Mat Morrison, planning director at marketing agency Digital Whiskey, told the BBC that Chinese advertisers had a history of using "provocative imagery" in an attempt to capture attention.

"Risqué, seaside-postcard style wardrobe malfunction-style adverts are a staple of the low-end publishers. They've created a tantalising advertisement that is just about 'clean' enough to pass publishers propriety rules, but salacious enough to capture audience interest. When someone clicks on it, the advertising network will place a retargeting cookie on their device that will let them identify them when they next see them.

Standard issue long johns in the army always had a back flap, nothing new here...

Standard issue long johns in the army always had a back flap, nothing new here...