Top officials in the city of Shenzhen will have to keep their spouses and families in China if they want to keep their jobs.

"Officials whose spouse and children have all emigrated to foreign countries should not take top positions in the Party and government," said a regulation issued by the Communist Party of China (CPC) Shenzhen committee and the Shenzhen government on Wednesday.

Shenzhen's regulation, containing 20 specific requirements for local top officials, is the first substantive enactment that restricts local officials' power and sets clear boundaries, media reports have said.

The initiative to improve supervision of top officials also suggests district- and city-level heads have no right to assign rights for using land.

The city, located in Guangdong province with a pioneering role in China's reform and opening up, is now set to become avant-garde in restricting the power of local Party and government chiefs on all levels.

Just half a year ago, Xu Zongheng, 54, was removed from his post as Shenzhen mayor for "serious disciplinary violations".

Last June, Pang Jiayu, former mayor and Communist Party chief of Baoji city in northeast China from 1997 to 1999, was accused of allowing substandard pipes to be used and sentenced to 12 years imprisonment for corruption.

But Pang's wife and son had emigrated to Canada in 2002, causing great concern in the public over corrupt officials relocating their "dirty money" abroad.

About 4,000 corrupt officials fled the country with at least $50 billion between 1978 and 2003, a report by the Ministry of Commerce showed. Many of these officials would send their spouses and children abroad first, then transfer the money they took from China.

Netizens are applauding Shenzhen's move.

"Shenzhen has discovered a channel of corruption. What they are doing should be extended to the whole nation," a netizen named "a tree outside the window" said on the Xinhua News Agency website.

However, at least one expert is raising questions.

"Is it enough to only focus on the Party and government chief?" said Tian Siyuan, a professor from the law school at Tsinghua University.

He said top officials are not the only ones who take bribes, while not all officials whose close relatives are abroad become corrupt.

He also wondered about those in lower positions who still have substantial power.

Tian said the most effective way to curb corruption is to disclose officials' assets and investments, as well as details of their family, as the CPC's Central Commission for Discipline Inspection demanded when it highlighted the fight against corruption during its Fourth Plenary Session in September in Beijing.

Earlier this year, the income of more than 1,000 officials in Altay prefecture in the northern Xinjiang Uygur autonomous region was made available to the public for the first time. The move required all county- and division-level officials in the prefecture to declare their assets once a year to improve transparency in government.

"However, since the central government has not currently issued a formal policy on asset declaration for high officials, we should still support any attempt from local governments to curb corruption, although they may not be perfect," Tian said.