State news agency Xinhua on Friday said an investigation had uncovered other evidence of Sun’s alleged crimes, suggesting the probe was not over. Sources said many more officials in Chongqing could be implicated.

Already, the party’s central leadership has rejected 14 out of 43 delegates proposed by the Chongqing authorities in May to take part in the 19th National Congress that starts on October 18. Their names were missing from the latest shortlist of delegates issued by Xinhua on Friday.

A total of 2,287 party delegates across the nation are to attend the congress in Beijing to decide the leadership line-up for Xi’s second term and to discuss and endorse major changes to the party charter.

It is unusual for a major region like Chongqing to lose one-third of its delegates just weeks before a party congress.

“Sun has offered [the graft investigators] detailed information about the wrongdoings of his subordinates since he was taken in,” a source familiar with the matter said, adding that the former Politburo member was hoping to get a more lenient sentence by reporting others.

“Five Standing Committee members of Chongqing’s party organisation and eight prefectural level officials have been questioned as a result,” the source said.

A media source in Chongqing confirmed this, saying that Sun had been forthcoming with information about the alleged misconduct of other cadres since he was detained on July 14, and he had confessed to the investigators “without any probing”.

Sun has been stripped of all official titles and handed over to judicial authorities for “further investigation”, meaning that he faces criminal prosecution.

Until Friday, he was one of the 25 members of the Politburo that forms the central leadership of the Communist Party. Sun is only the fourth sitting Politburo member to be brought down by a corruption investigation in 30 years. The previous one was also a Chongqing party boss – Bo Xilai – who was convicted of corruption and sentenced to life imprisonment in 2013.

The language used by state media on Friday to condemn Sun was even harsher than that used for Bo. However, a few hours after Xinhua reported Sun’s expulsion, it revised the wording to tone down the accusations.

The news agency initially said Sun “did not have any faith or belief [in communism]” and “seriously trampled on the party discipline and rules”. Later, it changed that wording to “Sun’s faith and belief was shaken” and he “seriously violated the party discipline and rules”.

While those changes may sound trivial, Xinhua’s reports on such matters are always carefully scripted and go through many layers of vetting and approvals before they are released.

“The change in wording could be a sign that this was a hasty decision made by the Politburo, and that it’s controversial even among the top decision makers,” said Chen Daoyin, a political scientist with the Shanghai University of Political Science and Law.

On top of these charges, Sun was also accused of being “lazy and inactive” and negligent in his duties. A Chongqing-based source close to the municipal government described him as “incompetent”. “Many people compare him with Bo Xilai and say they would prefer Bo over him. He’s not lazy – he’s simply incompetent,” the source said.

Another allegation was that Sun had leaked confidential party information. Sources said that could be related to the case of Mu Huaping, former vice mayor of Chongqing. Mu was sacked and put under investigation in April after an espionage case involving a Hong Kong woman who was said to be his girlfriend.

Five serving members of Chongqing’s Standing Committee have been disqualified as delegates to the party congress. They are Wang Xiangang, secretary general of Chongqing’s Party Committee, Zeng Qinghong, the female head of its Organisation Department, Liu Qiang, the top law enforcer in Chongqing, vice mayor Chen Luping, and Tao Changhai, head of the United Front Work Department.

A source said six out of 12 newly elected party officials in Chongqing could face investigation for corruption, meaning that the problem might be widespread and serious.

Some of the party officials who have lost their delegate status may not face prosecution and could still emerge from the investigation and keep their jobs.

Sun, who turned 54 on Monday, had generally been regarded as a key part of the party’s sixth-generation leadership when he became the youngest member of its decision-making Politburo in late 2012.

Former Shandong party Standing Committee member Hu Wenrong has been named as the replacement for Zeng at the Organisation Department, Chongqing Daily reported on Saturday.