China, which has over 457 million netizens, should be cautious about the emergence of 'Internet mercenaries', a group of people posting comments online to "manipulate" public opinion, a top Chinese official has said.

"We feel that Internet culture and environment is getting more complicated and there has emerged a group of people called 'Internet mercenaries'," said Zhao Qizheng, spokesman for the annual session of the National Committee of the Chinese People's Political Consultative Conference (CPPCC), apparently referring to the dissident groups making use of the net to call for anti-government protests.

CPPCC is an important organ of multi-party cooperation and political consultation under the leadership of the Communist Party of China (CPC).

The influence of public opinion through the Internet is getting stronger as more and more people use the net to exchange views and participate in political issues, the state run Xinhua news agency quoted him as saying.

China has over 100 million microbloggers, who have emerged as a new media in the country, challenging the hold of the state media.

Zhao said some of "mercenaries" backed by institutions for certain purposes, disguise them as ordinary netizens and post comments in order to affect and divert public opinion, or even disturb government policy-making, he said, adding China lacks legislation in this regard.

Dissident groups based in US during the past two weeks were attempting to whip of public protests similar to those witnessed in Gulf countries.

About persistent calls for declaration of assets by top Chinese officials, Zhao said it will be done in a gradual manner.

The disclosure of officials' assets takes time as China has nearly 10 million civil servants and a large number of people working in government-affiliated institutions, he said.

Currently, government officials are reporting not only about their income, property and investment, but also about whether their spouses or children live abroad, to the departments or institutions they work in, he said.

"Many things have to be done, step by step, before the definition of assets are made clear," he said.

Recently, online campaigners had urged people in 13 Chinese cities to rally every Sunday to press for government transparency and free expression, echoing those sweeping the Arab world.