Officials in Shenzhen are drafting rules that would protect well-intentioned rescuers from legal action if their efforts failed "as long as there was no negligence or deliberate sabotage", the China Daily said.

There have been renewed calls for such laws in China after the death last month of a two-year-old girl who was twice run over in the southern city of Foshan, which like Shenzhen is located in the prosperous province of Guangdong.

At least 18 people walked past the girl, nicknamed Yue Yue, as she lay unconscious in the street, in a case that shocked the nation and sparked much soul-searching about the state of China's morals.

Millions of Chinese went online to watch the grainy footage of the incident, which triggered speculation that the country's rapid development and urbanisation has made people more selfish.

Reports said the passers-by were likely concerned they would be held responsible if they stopped to help, after a high-profile 2006 case in which a driver who stopped to assist an elderly woman was later accused of knocking her down and sued.

Western countries including the United States, Canada and Australia, already have laws to protect rescuers from legal action, while in France people can be prosecuted if they fail to come to the aid of someone in danger.

But Zhou Chengxin, an official with the Legislative Affairs Office of Shenzhen, told AFP it would be the first such law in China.

Zhou said it was not clear when the draft law would be submitted to Shenzhen lawmakers for discussion.

Ai, whose 81-day disappearance in secretive police custody earlier this year caused an international uproar, has denied owing 15 million yuan ($2.36 million) in back taxes, calling the charge an attempt to quell his activism.

On Wednesday the artist and outspoken government critic, who was been ordered to remain in Beijing and refrain from giving media interviews after his release, used Twitter to condemn the Chinese authorities for their actions.

"They (authorities) have contempt for moral principles and judicial fairness," Ai posted on Twitter, which is blocked in China.

"All the ministries of this nation, these men and women, have no shame in becoming the tools of persecution of the political power.

"This really goes beyond the power of my imagination. I am shocked, it is a tragedy, I'm powerless," he wrote in Chinese, accusing China's Communist rulers of attempting to "wipe out dissent" with secret detentions and criminal penalties.

Ai has been given 15 days to settle the bill, which follows his release in June from a period of detention authorities said was over tax evasion but during which he said he was repeatedly interrogated over his calls for human rights.

The 54-year-old globally renowned conceptual artist, who is famous for his part in designing Beijing's "Bird's Nest" Olympic Stadium, told AFP by telephone on Tuesday he had received "no explanation whatsoever" for the tax bill.

Ai's detention in April came as scores of activists and rights lawyers were rounded up by police amid anonymous calls on the Internet for street protests in China similar to those that toppled governments in the Arab world.

The University of the Arts in Berlin has invited the artist to be a guest professor.

Germany's top human rights official Markus Loening said Tuesday the actions against him suggested political critics were being "willfully persecuted" in China.