BEIJING (Reuters) - A senior Chinese official who vigorously backed President Xi Jinping's fight on corruption has himself been caught up in a graft investigation, state media and the government said, becoming the latest victim of the high-profile campaign.

Mr Wang Min, Communist Party boss of Jinan city, is under investigation for suspected "serious breaches of the law and discipline", the party's graft watchdog said in a statement late on Thursday, using the usual euphemism for corruption. It was not possible to reach Mr Wang for comment.

Jinan, which lies about 300km south of Beijing, is the capital of Shandong province. Mr Wang also sits on the provincial party committee, equivalent to its ruling council.

The state-run Beijing Youth Daily said on Friday that Mr Wang had recently been speaking out on the need for clean government, giving a speech on the subject as recently as Thursday morning. He had also led an inspection tour of government departments this month to ensure they were following orders on how to fight corruption, the newspaper added.

Mr Wang, 58, is the most senior official from Shandong to face a graft investigation. The coastal province is home to many foreign-invested companies and factories, particularly from Japan and South Korea.

Mr Xi has vowed to go after corrupt officials and improve the legal system as he tries to restore faith in the ruling Communist Party after a slew of high-profile graft and abuse-of-power cases angered the public.

The government this month announced the arrest of former public security chief Zhou Yongkang, one of China's most powerful politicians of the last decade, on corruption and other charges.