Alibaba in Singles Day sales clash
China's two largest internet retailers have clashed in the run-up to Singles Day, the world's biggest online sales day, on 11 November.
Alibaba has been accused by its smaller rival JD.com of "forcing retailers" to promote their sales exclusively with its own outlet, Tmall.
JD.com has lodged a complaint with the Chinese industry and commerce watchdog but Alibaba denies the allegation.
The retail giant claims its rival is "panicking because they're losing".
"They simply can't match our customer and merchant experience and logistical scale because Alibaba wins with customers and merchants as we provide a superior experience for users on our platforms," said Jim Wilkinson, Alibaba's senior vice president of international corporate affairs.
The Wall Street Journal reported that a shoe retailer called Mulinsen had declined to promote JD's Singles Day event.
Singles Day began in the early 1990s as a day for people not in relationships to treat themselves, in the spirit of Valentines Day.
The Chinese State Administration for Industry and Commerce (SAIC) has accepted the complaint and warned retailers "not to use malicious marketing methods to engage in competition" ahead of the event, according to the Xinhua news agency.
A recent change in legislation bans online retailers limiting promotional activity by their merchants on other platforms.
Last year, Alibaba recorded $9.3bn (£5.9bn) sales during the annual event, which it adopted in 2009.