China’s largest online retailer files a complaint with the government, alleging pressure on merchants from Alibaba leading up to the country’s largest e-commerce event.

(Bloomberg)—The biggest rival to Alibaba Group Holding Ltd. in Chinese e-commerce is accusing the technology giant of violating market regulations and hampering competition in the runup to the nation’s largest online sales promotion.

JD.com Inc., No. 1 in the Internet Retailer 2015 China 500, filed a complaint this week with the State Administration for Industry & Commerce, the regulatory body overseeing consumer protection, according to JD’s official Weibo account. It said Alibaba told some merchants to not cooperate with other e-commerce platforms if they were participating in Alibaba’s Singles’ Day promotion this month.

Calling in the regulator is the latest twist in the battle between the companies for Chinese customers that has already seen Alibaba invest $4.6 billion for a stake in a retailer to challenge JD’s core strength of consumer electronics. Singles’ Day on Nov. 11 has morphed into China’s biggest excuse to shop, leading e-commerce operators to flood the Internet with promotions and discounts.

“After receiving reports from dozens of apparel retailers that a competitor is inappropriately pressuring them to pull out of JD.com’s Singles Day promotions, we have formally requested an SAIC investigation,” JD said in a text message.

Two phone calls to the SAIC’s market department went unanswered during non-working hours.

Alibaba, which started Singles’ Day in 2009, began replicating its success overseas last year, seeing sales spikes led by Russia. Last year more than 57.1 billion yuan ($9 billion) of transactions were conducted through Alibaba’s platform during the promotion.

“Alibaba welcomes competition as it benefits consumers, merchants and service providers. It also contributes to the growth and diversity of the e-commerce ecosystem, which in turn will benefit our business,” a Hong Kong-based spokesman for Alibaba said in an emailed statement.