It has begun. China’s largest Internet company says international users are starting to make in-roads into the dominance of Mainland Chinese users of its red-hot WeChat mobile messaging, according to a report by TechInAsia.

In an interview with the blog, Justin Sun, Tencent’s director of international WeChat operations, called the product the company’s “most important app,” the likes of which hasn’t been seen in 10 years at the company. That can only be a reference to the QQ instant messenger on which Tencent built its fortune. QQ, which was launched in 1999, has 700 million registered accounts. WeChat, which was born in January last year, already has 200 million users.

WeChat – called Weixin in China – is an instant messenger for mobile, but its most popular function is voice messaging. It also serves as a social network, with Instagram-like photo-sharing, a timeline, and easy friend-discovery functions. It’s like a hybrid of Whatsapp, Path, Instagram, Heytell, and GroupMe.

Mainland Chinese utterly dominated WeChat as of several months ago, accounting for close to 100 percent of users, but they no longer represent such a large majority, Sun said. Tencent is apparently starting its international expansion plans by focusing on Asia. Sun said the app’s biggest markets are Hong Kong, Taiwan, Singapore, Malaysia, Thailand, and Vietnam. “We’re really growing in the US and Arabic regions,” he added.

Tencent has already started marketing WeChat in places such as Taiwan and Malaysia. TechRice’s Kai Lukoff recently reported an encounter with a couple of scantily clad WeChat models in Taipei. The girls, who brandish cardboard signs proclaiming WeChat to be “the new way to connect,” provide personal guided tours to newbies on how to use the app. The mobile messaging sexpots have also been spotted in Kuala Lumpur.

Sun said the company doesn’t yet have an overseas office for WeChat and that its expansion will be managed on a country-by-country basis with local partnerships. That was the case for India, where WeChat partnered with leading social gaming portal Ibobo, in which Tencent holds a 20 percent stake. “We’re going to keep doing things ourselves first and keep those tight business partnerships with others,” Sun said.

He also stressed that WeChat is an open platform. The app allows integration of plug-ins – such as email and voice notes – that users can add to enhance the WeChat experience. You can also add your Facebook friends with the “Facebook Connect” option. “We must be connected and open to Facebook, Twitter and Instagram,” Sun said. “We must have the same strategy as them – we’re open.”

WeChat isn’t yet fully open as a gaming platform, but given Tencent’s history – it makes more than half its money from gaming – you can bet that will be just around the corner. South Korea’s KakaoTalk, which Tencent holds a 14 percent stake in and is similar to WeChat, launched its own gaming center in July. WeChat will almost definitely follow suit. For his part, Sun said only that WeChat “will be more open next year to gaming.”

Monetization in general, Sun said, is “not important” to WeChat right now. However, major brands are jumping on board anyway. Nike, Cadillac, and Starbucks have already launched campaigns on the platform. Expect to see a lot more to come. In fact, expect to hear a lot more from WeChat in general.