BEIJING -- China made public 20 severe cases of bribery in the construction sector Thursday, a fresh step in its fighting against corruption.

The 20 cases, made public by the Ministry of Construction, all involved government employees in charge of urban planning, project approval and evaluation of contractors' financial assessments.

Liu Zhifeng, Vice Minister of Construction, said most involved government posts where power and resources were relatively concentrated, and supervision was lax.

He cited Bi Yuxi, the former vice director of the Beijing Communications Bureau who was sentenced to death with a reprieve for embezzling state assets and taking bribes.

Liu said those offering bribes were seeking advantages in market competition and illegal profits.

"Bribes come in all forms. It could be cash, gifts or masquerading as an information, service or consulting charges, or school fees for their children," Liu said.

From January to July, China's procuratorial organs dealt with 1,608 corruption cases in construction sector, about 26.31 percent of the country's total.

"Because of the loopholes in rules and enforcement, the construction sector has turned into a hotbed of commercial bribery. The struggle is quite arduous," said Wang Jianming, director of the Bureau against Graft and Bribery under the Supreme People's Procuratorate.

China has intensified investigation of commercial bribery in sectors such as construction, land transfers, property right deals, medicine distribution and government procurement after Premier Wen Jiabao promised to crack down on bribery in the year's Government Work Report.