China Unicom, the country's second largest telecom carrier, said on Thursday it is building a nationwide network of Internet data centers which will be able to host 4 million units of computer servers.

Lu Yimin, China Unicom's general manager, said the company will step up efforts to build Internet data centers across China. "When completed, the total area of these data centers will exceed 2 million square meters." Lu said.

The company did not offer a timetable for the project, nor did it disclose the investment figure.

But it has already built six national-level Internet data centers and a dozen smaller data centers, which now are hosting roughly 1 million servers and cover 31 provinces.

The move comes as China Unicom is struggling to look for new revenue sources as the company's once lucrative business—text messages and voiced calls—is affected by Internet companies' social networking apps, such as WeChat.