Sina Weibo, China's version of Twitter, has effectively banned users from promoting the country's most popular messaging app WeChat on its platform as the two Internet giants battle for users.

NASDAQ-listed Sina Weibo said in a statement it would crack down on users disseminating QR (quick response) codes - a type of barcode - and other marketing information. QR code scanning is a main promotion method for WeChat.

Sina Weibo did not name WeChat, but the instant messaging platform widely uses QR to enable users to "follow" others by simply scanning.

State media portrayed the move as an escalation in the rivalry between the Internet giants. "War escalates as Sina Weibo bans users promoting WeChat," the official Xinhua News Agency reported Thursday.

WeChat, called "weixin" in Chinese, is owned by Shenzhen-based Tencent, and had 468 million monthly active users in the third quarter.

Sina Weibo, which has steadily lost users to WeChat, saw its user numbers drop 9 percent during 2013 to 281 million, data from the China Internet Network Information Center showed. Users say that WeChat is more versatile and easier to use.

Tencent currently also has its own microblogging platform Tencent Weibo, but has already ceased certain functions.

E-commerce giant Alibaba, a bitter rival of Tencent, holds a 32 percent stake in Sina Weibo.

Tencent and Alibaba have also locked horns. WeChat blocked promotion of Kuaidadi, a taxi hailing service backed by Alibaba, a week ago, Xinhua said.

Alibaba's consumer-to-consumer online shopping platform taobao.com and its online payment service Alipay have barred WeChat users as well, Xinhua noted.

WeChat users posting links to product listings on taobao.com are finding that the links cannot be opened, and are also currently unable to make or accept payments through Alipay.

Sina Weibo users could have their accounts suspended or be banned for violation of the new rule, the social network said, adding in a statement, "The cleanup operation is mainly targeted at accounts that do marketing in a coercive way."