Beijing (CNN) The "hottest" shopping destination in Beijing is putting one of the world's most popular clothing chains in the hot seat.
In a viral smartphone video posted Tuesday, a young Chinese couple can be seen having passionate sex in what appears to be a Uniqlo store fitting room.
A bespectacled man, dressed in black from head to toe, is heard telling a naked woman to kiss him as he tapes their steamy session in the mirror.
"Call me husband" and "say we'll be together" were a few of other phrases he uttered to her ear as piped music played in the background.
Then, toward the end of the video, another female voice -- over an intercom:
"Dear customers, welcome to the Uniqlo store at Sanlitun. There are no fitting rooms on the first floor. Please proceed to the second and third floor if you need to try clothes on."
The footage went viral overnight, attracting millions of views and thousands of comments. By midday Wednesday, however, most posts containing the clip had been taken down.
Beijing police announced online that they had received complaints about the video and would investigate the case.
Uniqlo: It wasn't us
Uniqlo is one of the world's biggest "fast-fashion" chains that has been quickly expanding its presence in the Chinese market.
Its three-story flagship store at Sanlitun, one of the trendiest retail and entertainment districts in Beijing, teems with shoppers throughout the day.
Some Chinese Internet users speculated the footage was a marketing ploy by Uniqlo, prompting the Japan-based company to issue a statement denying any involvement.
"As a responsible international brand, Uniqlo is dedicated to providing consumers with safe, comfortable and quality shopping experiences and locations," the company said. "We would like to remind all customers to abide by society's moral standard... and properly and appropriately use our fitting rooms."