Zhou was seen as a patron of fallen political star Bo Xilai, who he is said to have backed for a slot on the PSC, but whose career imploded after the death of a British businessman, for which Bo's wife was convicted of murder.

The decision to investigate Zhou was made in accordance with the ruling party's constitution, and the “discipline inspection authority's case investigation regulation,” China's official Xinhua news agency reported.

The decision will have been preceded by extensive negotiations within the factionalized ruling party, but is still likely to send shockwaves through the political establishment, as PSC members have long been regarded as untouchable even after retirement.

Analysts said that the move shows party chief Xi Jinping has now amassed enough power to break even longstanding taboos in his much-publicized anti-corruption sweep.

“There is an unwritten rule that they will not go after former members of the politburo standing committee,” said Willy Lam, a politics specialist at the Chinese University of Hong Kong.

“The party elders like Jiang Zemin and Li Peng and so forth were opposed to incriminating Zhou Yongkang,” he said, referring to China's former president and premier.

“It shows that Xi Jinping is powerful enough or resourceful enough to convince the party elders,” he added.

Xi has vowed to crack down on endemic graft among top party members, or “tigers,” as well as low-ranking members, or “flies,” but critics say he is unlikely to succeed without more fundamental reforms such as greater press freedoms and independent courts.

'Nab the tiger'

More than a dozen officials have been targeted in the sweeping probe into Zhou, with speculation mounting that the former security tsar himself would be soon to fall.For months, allies of Zhou in his powerbases in the southwestern province of Sichuan and China's state-owned oil giant CNPC have been targeted one by one by the ruling party's internal watchdog.

Earlier this month, three associates of Zhou — Ji Wenlin, Zhou's former secretary; Yu Gang, an ex-vice director of the office of the Central Politics and Law Commission (CPLC); and Tan Hong, a former senior staff officer of the Ministry of Public Security — were stripped of their Communist Party membership.

Yet China's state-run media steadfastly refrained from mentioning him by name until Tuesday, and the Communist Party's vast censorship apparatus swiftly swept away any mention of him on the country's popular social networking sites.

State-run broadcaster China Central Television (CCTV) mentioned the Zhou probe as the fourth item during its evening news broadcast, with an anchor taking less than a minute to read a brief version of the Xinhua report.

Even after authorities made the announcement Tuesday evening, searches for “Zhou Yongkang” on Sina Weibo — a Chinese Twitter equivalent — initially returned a message saying that results were not displayed “according to relevant laws, regulations and policies.”

The site later unblocked his name, and social media users quickly weighed in on the announcement: an hour after the news was first reported, “Zhou Yongkang” was the most-discussed topic on Sina Weibo, with 1.2 million postings.

“Finally, the noodles that have been cooking for so long are coming out of the pot,” one Weibo user wrote.

“There are hidden reasons behind it,” mused another.

“We support you, Chairman Xi,” another wrote. “You finally nabbed the tiger.”

北京探測前安全部長周永康

由費利西亞SONMEZ，法新社
2014年7月30日，上午12:04 TWN

北京 - 中國的執政黨共產黨已經把前安全部長周永康 - 它最強大的人物之一 - 正在調查中，但週二表示，最高級官員下降了幾十年。

週，誰從中國的全能退休政治局常委委員會（PSC）在2012年，被探測為“嚴重違紀”，執政黨的中央紀律檢查委員會，其內部看門狗，在一份聲明中說。

該術語通常用來指腐敗。

與傳聞已久的探頭正式公佈，週成為共產黨的最高級成員，因為四臭名昭著的幫會可查 - 一個派別，其中包括開國領袖毛澤東的遺孀 - 被放在試驗於1980年。

周某被視為墮落的政治明星薄熙來，據說他已備份的產品分成合同插槽誰，但他的職業生涯一個英國商人，為這波的妻子被裁定謀殺死後被引爆一個靠山。

調查週的決定是按照執政黨的憲法，以及“紀檢監察機關的案件查處監管，”中國官方媒體新華社報導。

該決定已經由之前的派別執政黨內部廣泛的談判，但仍可能通過政治機構派衝擊波，如力晶成員長期甚至退休之後被視為賤民。

分析人士稱，此舉顯示了市委書記習近平現在已經積累了足夠的力量打破甚至長期禁忌在他的很多宣傳反腐敗橫掃。

“有個不成文的規矩，他們不會去政治局常委的前成員後，”威利林，一個政治專家在香港的中國大學。

“黨長老像江澤民，李鵬等等都反對有罪的周永康，”他說，指的是中國的前總統和總理。

“這表明，習近平是足夠強大，或足智多謀足以說服黨內元老，”他補充說。

希發誓要打擊頂部黨員，還是“老虎”，以及低級別的成員之間，或地方性嫁接“蒼蠅”，但批評者說，他是不可能沒有更為根本的改革，例如更大的新聞自由成功，獨立的法院。

幾個月來，週中他在西南部省份四川和中國國有石油巨頭中國石油天然氣集團公司powerbases盟友一直在有針對性的逐項執政黨的內部監督。

十多名官員被瞄準的掃探入週，投機與安裝，前者的安全沙皇本人將很快下降。

本月初，周某的三家聯營公司 - 姬溫臨，周某的前任秘書; 餘剛，中央政法委員會（CPLC）辦公室的一名前副主任; 譚虹，公安部部前高級參謀 - 被剝奪共產黨成員。

然而，中國的國營媒體堅定不移地自提他的名字，直到週二忍住了，和共產黨的廣大審查機構迅速一掃任何提及他對國家的流行的社交網站。

國營廣播機構中國中央電視台（CCTV）在其晚間新聞播出提到的週探頭作為第四個項目，用錨服用不到一分鐘的時間讀完了新華社報導的簡要版本。

即使在當局宣布週二晚上，搜索“周永康”在新浪微博 - 中國的Twitter的等效 - 回到最初的消息說，結果未顯示“根據相關法律，法規和政策。”

該網站後來解封了他的名字，和社交媒體用戶快速權衡對公告：經過一個小時的消息被首次報導，“周永康”是討論最多的話題在新浪微博，擁有120萬的貼子。

“最後，已經煮了這麼久的麵條走出了鍋，”一個微博用戶寫道。

“有其背後隱藏的原因，”另一種沉思。

“我們支持你，主席奚，”另一位寫道。“你終於抓獲了老虎。”