A total of 129 officials at prefectural level or above have been investigated for suspected corruption and bribery in the first eight months of this year, the Supreme People's Procuratorate said on Thursday.

Prosecutors nationwide investigated 22,617 cases involving 30,938 people on suspicion of corruption between January and August, the top procuratorate said in a statement.

The number of cases was 3.6 percent higher than the same period last year, while the number of people investigated increased by 3.8 percent, and 7,080 of the cases came via tips from the public, the statement said.

A total 18,283 cases, or 80.8 percent, were classified as serious, an increase of 5.7 percent year-on-year, amid intensified anti-graft efforts.

The Chinese leadership has stepped up anti-corruption efforts this year and promised to go after both "tigers" and "flies", referring to high-ranking and low-level corrupt officials.

In the latest case, the discipline watchdog of the Communist Party of China said on Thursday that Ji Jianye, mayor of Nanjing, Jiangsu province, is being investigated for suspected discipline and law violations.

Ji, 56, is also deputy secretary of the Nanjing municipal committee of the CPC. He became acting mayor of Nanjing in 2009 and has served as Nanjing mayor since January 2010. He is accused of being linked to more than 20 million yuan ($3.2 million) in corrupt money.

Other officials that prosecutors have investigated this year include Liu Tienan, former deputy head of the National Development and Reform Commission; Ni Fake, former vice-governor of Anhui province; Wang Suyi, a Standing Committee member of the Party committee of the Inner Mongolia autonomous region; and Li Daqiu, a senior political adviser from the Guangxi Zhuang autonomous region.

The increased efforts show the determination of the new national leadership, led by President Xi Jinping, to fight corruption, said Zhu Lijia, a professor of government administration at the Chinese Academy of Governance.

"It also displays the leadership's efforts to bring the fight against corruption under a legal framework, as more corrupt officials were put on trial in recent months," he added.

In early July, former railways minister Liu Zhijun was given a suspended death sentence for taking bribes and abusing his power.

The investigation of Ji, the Nanjing mayor, generated discussion online.

"He is very unpopular in Nanjing," a netizen said on his Sina Weibo micro blog. "Uprooting so many plane trees alone is a severe crime."

Under Ji, a large number of valuable trees in Nanjing's urban areas were relocated or destroyed to make way for subway construction, a move that generated strong public opposition.

Xinhua contributed to this story.

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