China's senior leadership has agreed to open a corruption investigation into Zhou Yongkang, one of China's most powerful politicians in the past decade, stepping up its anti-graft campaign, the South China Morning Post reported on Friday.

The move against Zhou - a retired member of the Politburo's all-powerful Standing Committee - follows the five-day corruption trial of ousted politician Bo Xilai, who was widely considered a key Zhou ally.

The Foreign Ministry declined to comment on the report when contacted by Reuters. The State Council Information Office, the public relations arm of the government, did not respond immediately to faxed questions about the report from Reuters.

Zhou also could not be reached for comment on the report.

He was one rank higher than Bo in the power structure and would be first Politburo Standing Committee member - retired or sitting - to be investigated for economic crimes since the end of the Cultural Revolution nearly 40 years ago, the newspaper said.

Citing sources familiar with the leadership's thinking, it said the decision to investigate was made in view of rising anger inside the party at the scale of the corruption problem and the wealth that Zhou's family has amassed.

President Xi Jinping ordered officials in charge of the case to "get to the bottom of it", the paper said.

Chinese authorities also revealed this week a probe into China National Petroleum Corporation (CNPC), which Zhou joined as a senior manager in the early 1990s. Four top managers at the company have been named as being under investigation in recent days.

The newspaper said it understood the new probe would centre on Zhou's time in Sichuan and at CNPC.

In particular, investigators would examine whether Zhou and his family benefited through oilfield and property deals facilitated by his son, Zhou Bin, and other allies, it said.

Sources told the newspaper it was too early to say whether Zhou - who controlled legal and law enforcement affairs for 10 years from 2002 - would face public prosecution or an internal party probe.

Former Chongqing party boss Bo is awaiting a verdict on corruption charges.