Beijing:  Police in China have arrested an influential blogger and are holding a cartoonist in a widening crackdown on online "rumour-mongering", friends and a lawyer for one of them said today.

Hundreds of people have been detained since August, say Chinese media and rights groups, as the government has stepped up its campaign to banish rumours. Most have been released, but some are still being held on criminal charges.

The latest moves targeting the bloggers appear to suggest the new government, led by President Xi Jinping, is expanding its crackdown on dissent, although some critics have warned the move could backfire on Communist Party leaders.

"The use of these dictatorship tools to combat the criticism and grievances within civil society could be counterproductive," said Zhang Lifan, a historian, adding that it could fuel mistrust. "It may not be beneficial for maintaining the regime."

Dong Rubin, 51, who runs an Internet consulting company, has been arrested in southwestern Kunming on "suspicion of falsely declaring the capital in his company's registration", state news agency Xinhua said late on Wednesday.

Dong was also suspected of illegal business operations and the crime of "creating disturbances", Xinhua added.

Dong, who was previously invited by officials in southern Nanjing to speak about being an "online opinion leader", is well known for participating in a 2009 online probe into the sudden death of a man in a detention house in Yunnan province.

State broadcaster CCTV showed images of Dong admitting to "exaggeration and selectively publishing information" to benefit clients. In September, state media also aired a confession by Chinese-American venture capitalist, Charles Xue, one of China's best known online commentators.

Dong's lawyer, Yang Mingkua, told Reuters by telephone it was not convenient for him to be interviewed, but referred to a legal opinion published on his microblog.

"When the air is filled with voices that are unharmonious, that is not a sign of weakness, but a symbol of strength," Yang wrote on the microblog in September, describing Dong's case. "The freedom to speak and criticise is a citizen's right."

Yang said Dong believed he was "fundamentally innocent" in his actions on the Internet.

In Beijing, the capital, cartoonist Wang Liming was taken into custody at midnight on Wednesday and has not yet been freed, his friend, Wu Gan, told Reuters by telephone.

Wu said police told Wang's girlfriend they summoned him for forwarding a microblog post about a stranded mother holding a baby who had starved to death in the flood-hit eastern city of Yuyao.

"Suppression of this kind by the Chinese government is of no use," Wu said. "Rumours arise because there's no freedom to communicate on the Internet. Arresting people will not solve the problem because the problem does not lie with the people, but with the government."

The detentions come slightly over a month after China unveiled tough measures to stop the spread of what it calls irresponsible rumours, threatening jail terms of three years if untrue online posts are widely reposted.

China's top court and prosecutor have said people will be charged with defamation if online rumours they create are visited by 5,000 internet users or reposted more than 500 times.

Liu Hu, a Chinese investigative journalist accused of corruption was arrested on a defamation charge late in September, his lawyer said last week.

The Internet clampdown reveals the insecurity of the leaders of the ruling Communist Party, said Bo Zhiyue, a professor of Chinese politics at the National University of Singapore.

"They are trying to send China back all the way to the Stone Age," Bo said. "Where is the hope for political reform? Zero."