BEIJING - Sina Weibo, the Chinese Twitter-like micro blogging site with over 200 million users, revealed its annual roundup on Wednesday, summing up this year's most heated topics on a website that has arrived on the scene as a major forum for public opinion.

Unsurprisingly, first place went to the fatal high-speed train collision in July, which spawned millions of posts railing against the railway authorities, mourning the victims, and calling for thorough investigation of the crash's causes.

While Twitter keeps on the rails as a pure social networking site, its Chinese counterpart, Weibo, acts more like China's Hyde Park -- an open space where people feel free to participate in public affairs.

As a popular post on Sina Weibo said, "When we surf Weibo, affairs of the state pour into our minds, requiring us to make our own judgement and responses. An emperor is hidden in everyone's heart, and Weibo just activates the complex."

Weibo started flexing its muscle in public affairs in January when a post by a well-known scholar snowballed into a national campaign clamping down on child abduction, a topic ranking third on the website's billboard.

Yu Jianrong, a researcher with the Chinese Academy of Sciences, tweeted a post searching for kidnap victims-turned child beggars, prompting Weibo users to swathe the Internet with photos of street children.

Responding to online appeals, the Ministry of Public Security launched a crackdown on human trafficking and promised no child beggars will be seen in cities by the end of 2012.

"Weibo also ramps up transparency in public affairs," said Xia Xueluan, professor of sociology with Peking University. Officials and authorities must act more gingerly, since they no longer feel free of restraint but under constant supervision from the people, he said.

Xia's remarks were reflected in the roundup list, which included an alleged embezzlement scandal that battered the Red Cross Society of China (RCSC).

In late June, a 20-year-old woman calling herself "Guo Meimei" claimed to be a general manager for "Red Cross Commerce" and detailed her lavish lifestyles on Weibo, provoking public fury against her suspected use of the the RCSC name for embezzlement.

Though the RCSC constantly denied any links with Guo, donations to the aid agency plummeted amid the crisis of trust, according to one of its senior executives last week.

Meanwhile, the authorities have begun to take the initiative to enhance public trust with the help of Weibo.

Weibo actually gave the authorities a new approach to adhering to the "mass line," Xia said, referring to a government working method that upholds serving the people.

The number of Weibo accounts verified as being managed by government officials or departments quadrupled to 20,000 in 2011, according to a report issued by Sina Corp, while "Improving guidance of public opinions in the Internet era" has been added to the syllabus at the Chinese Academy of Governance, where senior government officials are trained.

The Shanghai government was widely praised for its good use of Weibo. In early December, Shanghai City, the official Weibo account of the  Information Office of the Shanghai Municipal Government, posted appeals online to help farmers sell overstocked cabbages.

Though Weibo has many flaws, it has sparked progress in Chinese society and the Chinese government, Xia said.

As the first Weibo post of Shanghai City put it, "We are open to hearing voices of residents. We sincerely welcome supervision and communication."