Chinese Web portal operator Sina Corp, which runs the country's most popular micro-blogging service Sina Weibo, expects advertising sales to improve this year as the economic climate warms.

However, analysts said they had mixed views on the company's optimism for a successful monetization of Weibo anytime soon, amid rising competition from rivals like Tencent Holdings Ltd.

During an earnings update on Wednesday, Charles Chao, Sina's chairman and chief executive officer, said its key sectors of automobile, financial and fast-moving consumer goods will grow fast this year.