360buy, the biggest 3C online retailer in China was reported early today that it had stopped using Alipay, the most popular online payment gateway as one of its payment methods.

Alipay’s official comments on this is that it’s due to system maintenance, and emphasized the service would be back today. There is no any official statement from 360buy so far. The weird part is that even on the 360buy’s Q&A page, Alipay also disappeared from the payment method section.

Alipay is now the No.1 third-party payment gateway in China, and is reported 500millions users by October 2010. 360buy has raised over US$1 billion in its series C of funding recently and the company is aiming at rmb 100billion transaction volume in next 5 years. If 360buy stops the partnership with Alipay as people suspected, it sounds like triggering a war and could be a big hit to the online payment market in China. Rumor says 360buy is unhappy that Alipay is taking all its users’ profile and is planning to launch its own payment solution.