Signs of a serious division within the ruling Communist Party of China are emerging over a crackdown on corruption led by current leader Xi Jinping, according to a recent U.S. intelligence report on the division.

The political rift is being linked to a nationwide anti-corruption drive launched by Chinese President Xi Jinping, and to differences among top leaders over the purge of several of China’s most senior leaders who held posts at senior Party levels that in the past were immune to such crackdowns.

Corruption in China—bribery, graft, and abuse of power—remains a key feature of the reform communist system in place since the 1980s.

The recent unclassified intelligence report circulated within the U.S. government disclosed that the leadership rift is linked to the case against Zhou Yongkang, a former member of the Politburo Standing Committee, the seven-person collective dictatorship that rules China.

Analysts of China have long argued that leadership divisions in China would be among the indicators of a breakdown of one-party rule that could produce a change in a system in place since the Communists seized power in 1949.

Zhou, considered Party’s most senior security chief and one of the most powerful leaders in China, has been under investigation for corruption since at least July.

The probe is part of a campaign by Xi, the Party’s general secretary, that began in January 2013 targeting what Xi said were both "tigers" and "flies"—high-level corrupt officials and lower-level party cadres. At least 50 higher-level Party officials have been charged in the campaign, along with thousands of lower-level bureaucrats.

Disclosure of the divisions comes as China is hosting an economic summit in Beijing for world leaders. It also follows a recent Party conference that called for increasing Chinese-style rule of law, a western-sounding concept that in China translates into the use of laws to maintain the Party’s power—not to maintain an independent judicial system.

One key sign of the leadership dispute appeared briefly last summer in an online version of the Party newspaper Changbaishan Ribao.

The newspaper, an official mouthpiece for the regional Party in Baishan City, Jilin Province, quoted Xi as telling a close-door meeting of the Politburo on June 26 that "the two armies of corruption and anti-corruption are in confrontation, and are in a stalemate."

Shortly after the article appeared it was removed by Chinese censors, an indication it had revealed sensitive internal information.

"The move against Zhou violates an unspoken rule against investigating retired Political Bureau Standing Committee members," the intelligence report said, noting that the hands-off policy has been a key factor in maintaining political stability in Cultural Revolution elite politics.

"If this assumption is correct, then violating this rule could increase division within the leadership," the report said.

During the Cultural Revolution of the late 1960s, Communist founder Mao Zedong unleashed Party zealots known as the Red Guard against established Party leaders and institutions. The conflict threw China into chaos and ended with the arrest of Mao’s widow and three other top leaders known as the "Gang of Four." Communist reformer Deng Xiaoping then assumed power in 1980 and launched the current reform period.

Reports from Asia also reveal that Xi’s anti-corruption campaign has produced "tension among members of the elite, some of whom may be concerned that their privileges are under threat," the report said.

The report also quoted the editor of the Party history journal Yanhuang Chunqiu as saying: "In society there is the saying that ‘[Political Bureau] Standing Committee' members are immune from punishment,' which has been viewed as an unspoken rule."

The report did not elaborate on the factions involved in the dispute.

However, Zhou’s case has renewed calls on China’s vibrant Internet chat rooms for political reform and constitutional democracy.

State-run Chinese media also have sent mixed messages about whether additional high-level officials will be charged in the anti-corruption campaign.

Some Party propaganda outlets have stated that Zhou is not the last senior official to be ousted.

However, an analysis of the Xi anti-corruption drive reveals it has been focused on senior officials in China’s northeast Liaoning province.

All three of the so-called disgraced senior leaders, dubbed "tigers," belong to the Liaoning faction, including Zhou, former Central Military Commission Vice Chairman Xu Caihou, and Chongqing Party boss Bo Xilai. Bo was ousted in 2012 and later imprisoned on bribery, abuse of power, and corruption charges. Xu was ousted in 2013 for selling military ranks. All three began their careers in Liaoning.

Another bastion of corruption is the Party organization in north central China’s Shanxi Province, where four members of the regional 13-member Politburo Standing Committee are under investigation for corruption. A total of 29 Shanxi officials are under investigation or have been expelled so far.

The intelligence report said the Communist party is gambling that the anti-corruption campaign will boost the legitimacy of the Party. "The party's bet can pay off if it successfully frames the Zhou case as proof of the effectiveness of its anticorruption institutions rather than the result of a power struggle," the report said.

Additionally, the Party is trying to convince the public that battling corruption will not require restructuring the communist system.

"The party can lose its bet if investigating Zhou does not boost its legitimacy or if it causes increased division among the elite that leads to high-level political instability," the report said.

Other indicators of internal leadership divisions among Chinese leaders included subtle differences on political and economic reforms.

"Clearer divisions—which would suggest increased leadership division—would likely first emerge in commercial media, then in party journals such as those of the pro-reform Central Party School and the more conservative Chinese Academy of Social Sciences, and finally in authoritative media," the report said.

Another sign of leadership divisions within the Party is the length of time it is taking for the Zhou investigation to be concluded. Zhou is facing graft charges and normally the regime completes its investigation of senior leaders within two months. The delay in the case is fueling speculation that leaders remained deadlocked over how to handle the case.

As the former security chief, Zhou is believed to have numerous allies within the Party leadership and the military and intelligence services.

China’s vice minister of justice, Zhang Sujun was quoted last week in the South China Morning Post as saying there would be no comment on the Zhou case until investigators complete their work.

"[We] will make an announcement to the public when the investigation has come to a specified stage," Zhang said in Beijing.

Randy Schriver, a former State Department and Pentagon policy maker involved in China affairs, said it is difficult to assess China’s leadership struggle because of the closed nature of the system.

"Given the aggressive nature of anti-corruption efforts in China, and the pervasive nature of corruption itself, a backlash is almost inevitable" Schriver said. "Presumably this is all part of Xi's calculus, but it's a risky endeavor nonetheless. It's probably further evidence of the fragility of the Party and concern about the populace if Xi is willing to take these risks."

A U.S. intelligence community official had no immediate comment.