Pledges for more transparency by top Chinese Communist officials made following high-profile graft cases have been met with scepticism that corrupt leaders can come clean over their assets.

Wang Yang, the top Communist official in the southern province of Guangdong, and Yu Zhengsheng, the party boss of Shanghai, both said Friday that Chinese officials would begin releasing details of their assets in the future.

"I believe that Chinese officials will gradually make assets public in line with central regulations," Wang, seen by many observers to have reformist leanings, said during a Congress meeting in answering a foreign reporter's question.

Yu, meanwhile, said separately that Shanghai would "gradually move towards a system for making (officials') assets public," according to the state-run People's Daily.

But neither official provided any road map forward for improving transparency in a country that has no laws that clearly require government officials to make their assets or salaries public, a situation critics say is ripe for abuse.

The issue of official corruption has shot to the top of the national agenda as Communist Party delegates meet to anoint a new crop of top leaders for the coming decade.

China's ruling Communists have been scandalised for years by persistent reports of corrupt officials living lavish lifestyles and keeping multiple mistresses, and complaints that their iron grip on power prevents accountability.

But the issue has sharpened in the run-up to the congress in Beijing after a traumatic year for the party marked by embarrassing revelations of top-level corruption and power abuse.

President Hu Jintao, in a speech opening the congress in Beijing on Thursday warned starkly that corruption "could prove fatal to the party" and even cause its "collapse".

Among the recent shocks, the New York Times reported last month that the family of Chinese Premier Wen Jiabao owned assets worth $2.7 billion.

Earlier this year, Bloomberg news agency estimated the family of Xi Jinping -- who is almost certain to be appointed head of the party during the congress, and named president next year -- had assets worth $376 million.

Authorities have sought to suppress the reports in China.

Several local governments have pledged to disclose official's assets in recent years, but these schemes were abandoned after running into "difficulties", the state-run China Youth Daily reported recently.

"The disclosure of assets is opposed by corrupt officials," Peking University law professor Jiang Mingan was quoted telling the paper, adding that top leaders fear revelations of large assets held by officials could further stoke anger.

State media reports have said government departments have refused hundreds of private requests from citizens to disclose details of official salaries.

Wang and Yu are under intense scrutiny during the congress, as both are considered contenders for promotion to the top echelons of power in Beijing.

But their remarks prompted cynical comments from users of Weibo, the wildly popular Twitter-like Chinese micro-blogging service whose users have helped expose some cases of corruption among local-level officials.

"Talk is easy." one user wrote of Yu's comments.

"His public statements fool the masses, but in private he'll work to prevent disclosure," wrote another.

In the most sensational and damaging corruption case in years, Bo Xilai, a regional party boss in southwestern China and former rising star, was toppled this year in an affair involving a murder conviction for his wife.

Bo will soon face trial on allegations of corruption and power abuse.

Other cases of egregious corruption arise regularly.

In one, an official in the southern Chinese city of Guangzhou was placed under investigation last month after Internet users posted pictures of some of his 23 houses.

The public resonance of the issue was made clear when Zhang Tiancheng, an official in southern China's Hunan province, was hailed as a hero for using Weibo to post details of his family income and assets in late October.

Among other details, Zhang listed his approximately 3,000 Yuan ($480) monthly wage, his love of reading, fishing and "attractive women".

"He is truly a servant of the people," one Weibo user responded in a typical reply. "I wish he could be a role model for the rest."