BEIJING (REUTERS) - China's top graft-buster has told the country's state-owned industries that they also have a responsibility to follow the ruling Communist Party's rules on fighting corruption, state media said on Tuesday, as Beijing broadens its graft campaign.

Chinese President Xi Jinping has vowed to target powerful "tigers" as well as lowly "flies" in a fight against corruption that he has said threatens the Communist Party's very existence.

The party has already set its sights on the state-owned energy sector, including State Grid Corp of China, PetroChina , and its parent firm, China National Petroleum Corp (CNPC).

In March, the chairman and the president of Three Gorges Corp., the company that built the US$59 billion (S$73.8 billion) project for the world's biggest hydro-power scheme, stepped down, but they have not been accused of any wrongdoing.

"Responsible people at central state organs, central industries and state-own financial organisations must not forget their positions in the party and their responsibilities," Mr Wang Qishan, who leads the party's fight against corruption, was quoted as saying in the official People's Daily.

"Firmly grasp that not following the party's rules on clean government is a dereliction of duty, never merely focus on business and ignore party rules or only look at development targets and not on punishing corruption," Mr Wang added.

Those who fail to follow these instructions will be held to account, he said.

This year, state-owned companies had to "shoulder the responsibility" for fighting corruption, Mr Wang added. He did not mention any specific companies or sectors which the government may target.