BEIJING - Despite persistent campaigns and tough penalties in recent years, corruption in infrastructure projects is still pervasive, China's anti-graft agencies have warned.

According to the Central Commission for Discipline Inspection of the Communist Party of China, the country's key anti-graft agency, over the first eight months of this year, about 6,800 officials have been prosecuted for corruption in infrastructure projects across the country.

And prosecutors uncovered graft cases in this sector involving more than 2.99 billion yuan ($468 million) during a nationwide campaign from Sept 2009 to March this year, according to the Ministry of Supervision.

Local prosecutors closely involved in corruption investigations have found that bribery is now included as a regular part of many contractors' budgets as "public relations expenses".

Given that the nation has spent a huge amount of money on infrastructure development in recent years, the amount of money involved in graft cases has increased notably.

A bribe may exceed 1 million yuan if the project is estimated to cost 20 million yuan, said a city prosecutor in Jiangxi province, who asked to remain anonymous.

"In most cases, bribes make up 5 to 10 percent of the total cost of a project," he said.

The bribery occurs in many stages of a project, including land-use approval, project management, public bidding, the purchase of construction materials and equipment as well as project inspections, said Zhang Xin, a provincial prosecutor in Jilin province.

Besides accepting outright cash, officials receive shopping vouchers, dividends, overseas tour packages, school tuition for their children, houses and luxury goods, Zhang said.

Prosecutors have also found that chief officials in government departments or State-owned enterprises related to infrastructure development are susceptible to corruption.

Last week, Wu Rijing, a former chairman and general manager of the State-owned Guangdong Xinguang International Group, stood trial at a local court in Guangdong province charged with accepting more than 26 million yuan in bribes, offering bribes of more than 1 million yuan, and embezzling more than 46 million yuan of public money.

Prosecutors say all the crimes occurred when Wu was in charge of subcontracting construction projects between 2006 and 2008.

Since March 2007, 10 senior officials in Jiangxi's provincial transport department have been sacked due to corruption, including Pu Rixin, the department's former director, who was charged in June with taking bribes amounting to 4.23 million yuan.

Lack of effective supervision enables chief officials to misuse their power. Anti-graft agencies need to cooperate with the government financial supervision and auditing agencies and set up an information-sharing platform and blacklist contractors involved in graft cases in order to stop them from bidding for other projects, Zhang said.

In recent years, the government has stepped up its efforts to crack down on corruption in construction projects. Further reform of construction project management and increased supervision of chief officials.

Infrastructure projects have been one of the four priorities of the country's discipline supervision work, said He Guoqiang, head of the Central Commission for Discipline Inspection of the Communist Party of China, at a meeting last month.

Xinhua