CATL, which produces more than a third of the EV batteries sold worldwide, filed a 527-page document to the Hong Kong Stock Exchange with offer-related information redacted.

It is the first step in what analysts say could be a jumbo initial public offering that could boost Hong Kong's fortunes as a listing hub.

"This Application Proof is in draft form," the firm said in the document, which includes financial information and corporate details with redactions.

CATL said in another exchange filing dated Tuesday it has "appointed... overall coordinators" and listed seven financial institutions.

The company is publicly traded in Shenzhen and its plans to seek a secondary listing in Hong Kong were announced in an exchange filing in December.

Founded in 2011 in the eastern coastal Chinese city of Ningde, CATL has grown into the world's largest EV battery maker and supplies firms including Mercedes-Benz, BMW, Volkswagen, Toyota, Honda and Hyundai.

In January, the US Department of Defense added CATL to a list of companies it says are affiliated with Beijing's military.

China has denounced the move as "suppression", while CATL denied engaging "in any military related activities".