Chinese-owned online marketplace Temu has reignited its legal feud with fast-fashion brand Shein in the US, citing an “intensified” series of anti-competitive actions.

This development reignites the fierce competition between the two companies, which appeared to have waned after both companies withdrew previous lawsuits against each other in October.

In a 100-page filing submitted to the US District Court for the District of Columbia, Temu asserted that Shein orchestrated a “desperate plan” to undermine its business.

The complaint alleges a range of anti-competitive practices, including the filing of 33,000 copyright takedown notices against Temu, coercing fashion suppliers into exclusive agreements, and even resorting to threats and detentions of Temu merchants.

Both companies are emerging Chinese players in the global e-commerce arena and pose a growing challenge to established giants such as Amazon, Walmart, H&M and Zara.

Temu, which entered the US market in late 2022, attributes a decline of more than $30bn in Shein’s valuation, which originally exceeded $100bn, to its presence. The lawsuit alleges that Shein devised a “desperate plan” to eliminate Temu’s competitive threat.

Shein, which has confidentially filed for an initial public offering in the US, targeting a valuation of up to $90bn, denies the accusations.

Temu’s new lawsuit goes beyond copyright infringement and supplier coercion, accusing Shein of attempting to poach key marketing executives and replicating promotional strategies.

The latest legal skirmish unfolds as Temu continues to outpace Shein in US transactions since May, widening the lead every month.