Nokia's plans to launch its Windows Phone 7.5 Mango smartphones in the China market in the first half of 2012 may face challenge from comparable high-end models rolled out by HTC and Samsung Electronics as well as entry-level models by ZTE, Huawei Device and Lenovo, according to industry sources.

Although Nokia has launched its Mango phones in Europe and a number of markets in Asia, it has not yet introduced the models into China, the largest single market for Nokia, as it needs time to integrate the phones with local mobile network services in China, the sources indicated.

However, Nokia may lose its advantage if it delays the launch of Lumia phones in China to the second quarter of 2012, since rivals HTC and Samsung are likely to roll out comparable high-end Mango models any time soon, said the sources, adding that major China-based handset makers such as ZTE, Huawei and Lenovo all have ventured into the development of Mango phones.

Furthermore, Microsoft plans to lower the hardware specifications for smartphones running on its Tango OS - a move which is likely to encourage China-based handset makers to bring out low-priced Tango phones to compete with Nokia Lumia phones, the sources added.