A high-level Chinese official is being investigated for "breaching party discipline" just weeks after he was promoted to one of the country's most powerful ruling bodies, potentially underscoring the gravity of a new anti-corruption drive spearheaded by China's new top leadership.

China's anti-corruption commission has opened an investigation into Li Chuncheng, the deputy party secretary of south-western Sichuan province, China's Xinhua state newswire reported on Wednesday. Li missed an important provincial meeting on Tuesday and has not been seen in public since 19 November, Xinhua reported, without explicitly stating that he was detained or listing any alleged transgressions. As of Wednesday, the article had been removed from Xinhua's website.

Li spent most of his career ascending the Communist party ranks, beginning in the frigid northern province Heilongjiang in the mid-1980s. He became the mayor of Chengdu City, Sichuan province, in 2001, which soon vaulted him into higher provincial posts. Li was named an alternate member of the Communist party's powerful 205-person central committee during the once-in-a-decade leadership transition last month.

Jean-Pierre Cabestan, a Chinese politics expert at Hong Kong Baptist University, said: "That's raising a lot of questions, because it means the guys who were in charge of creating these leaders – shortlisting the committee members – overlooked their backgrounds. It creates an impression of dis-coordination."

The Hong Kong-based South China Morning Post wrote that Li was being held under shuanggui, a notoriously harsh extrajudicial form of interrogation.

China's leadership is still reeling from a series of corruption scandals this year, starting when Bo Xilai, one of China's most powerful politicians, was sacked for corruption and abuse of power in the spring. Exposés by Bloomberg and the New York Times have revealed the vast wealth accrued by the families of top leaders – including new general secretary Xi Jinping, and the departing premier Wen Jiabao – leading internet censors to block both organisations' websites.

Analysts say that uncommonly strong anti-corruption language in Xi's speeches, coupled with the appointment of a no-nonsense financial expert, Wang Qishan, as head of the country's anti-corruption commission, signal that the new party leadership is likely to take a tough stand on abuses of official power.

"A great deal of facts tell us that the worse corruption becomes the only outcome will be the end of the party and the end of the state," Xi said at a politburo "study session" soon after he was named the party's general secretary, state media said.

He called for an end to a long list of officials' conspicuous consumption habits in a statement carried by state media on Tuesday. Officials were instructed to shun red carpet treatments, cut down on elaborate floral displays, publish fewer books, limit traffic-disrupting motorcades and do away with oversized overseas delegations.

Xi, whose charisma sets him apart from his notoriously wooden predecessor Hu Jintao, also instructed media outlets to trim their coverage of official activities that lacked real news value. "What you ask of others, first do yourself," he said. "What you tell others not to do, you must absolutely not do."

Yet some experts are skeptical that Xi's anti-corruption rhetoric will precipitate any real change. "There's a strong impression of deja vu here," said Cabestan. "Of course he wanted to mention these things, because they're the most visible manifestation of privileges, and that's what irritates a lot of people in China."

China fell from 75 to 80 on this year's Corruption Perceptions Index, which was released by the Berlin-based nonprofit Transparency International on Wednesday. It now ties with Serbia and Trinidad and Tobago. 176 countries were surveyed; the UK is ranked 17.

Aggrieved Chinese citizens are increasingly turning to popular microblogging websites to expose corrupt officials. Chongqing official Lei Zhengfu was sacked last week after a 12 second-long, five-year-old tape showing him having sex with a teenage woman went viral on the microblogging website Sina Weibo.

According to the investigative reporter who leaked the video, a construction company had bribed Lei with young women to secure project approvals and then blackmailed him with videos of their trysts.

• This article was amended on 6 December 2012 because the original described Xi Jinping as China's new president. As the new general secretary of the Communist party, he is expected to take up that post next year.