BEIJING, Dec. 9 -- The handing of Zhou Yongkang, once one of the most powerful officials in China, over to prosecutors on Friday marked the climax of this year's anti-corruption drive.

Zhou, one of nine Standing Committee members of the Political Bureau of the Communist Party of China (CPC) Central Committee from 2007 to 2012, is the latest and highest-ranking official taken down in the country's fierce anti-corruption campaign that began in November 2012.

"Nailing a high-ranking official like Zhou sends a strong message to all senior officials. It supports the Party's zero-tolerance policy against corruption," said Huang Weiting, a researcher with Seeking Truth, the official magazine of the CPC Central Committee, who has closely followed the anti-corruption issue.

However, China's anti-graft campaign has moved beyond setting warning examples to deter others. The scale of the investigations, as well as new initiatives and legal reform, indicate that the country intends to fight a protracted war.

The CPC leadership has realized that they face an unprecedented situation and serious challenges in leading a party of 86 million members and ruling a country of 1.3 billion people for the long term.

"Although the majority of CPC members are dutiful and well behaved, corruption has been a prevailing problem and will be a serious threat to the Party's rule of the country if not well contained," Huang said.

The CPC leadership is fully aware that its ability to discipline its own members, especially those with power, will affect its capacity and stability to rule, he said.

President Xi Jinping told media when he was elected general secretary of the CPC Central Committee in late 2012 that to address these problems, the CPC must "first of all conduct ourselves honorably."

At a CPC disciplinary watchdog meeting in early 2013, Xi also vowed to make no exceptions when it comes to Party discipline and law and to give no leniency, no matter who is involved.

TIGERS AND FLIES

Practice has been in line with the leader's words. Graft-busters have swept the military and civilian sectors, central and local governments, state-owned enterprises and public institutions.

According to the website of the CPC Central Commission for Discipline Inspection (CCDI), about 50 officials at the provincial and ministerial level or higher have been investigated for corruption or other serious disciplinary violations since November 2012.

In China's bureaucratic system, officials at this level and above are important decision makers on central and local affairs.

Another high-ranking official alongside Zhou was Xu Caihou, former vice chairman of China's Central Military Commission. The investigation into Xu ended and the prosecution process began in late October.

A majority of these "tigers," a popular term for high-ranking corrupt officials, were senior provincial officials and chief officials of provincial capitals. North China's Shanxi Province has seen five members of the standing committee of the CPC Shanxi provincial committee, the province's top decision-making body, put under investigation for disciplinary violations.

There were senior officials of central government departments, such as Jiang Jiemin, head of the State-owned Assets Supervision and Administration Commission, and Li Dongsheng, vice minister of public security.

Some were from state-owned enterprises and public institutions, such as Song Lin, former chairman of China Resources, and He Jiacheng, executive vice president of the Chinese Academy of Governance (CAG).

Discipline inspectors have also tightened their grasp on low-ranking corrupt officials, who have been dubbed "flies."

In the first half of this year, 84,000 officials nationwide received disciplinary punishment, a year-on-year rise of 30 percent, while prosecutors filed graft cases against 35,600 people from January to September.

REGULAR INSPECTIONS AND A "FOX HUNT"

Some efforts might not be as sensational as sacking a heavyweight, but they have still made a profound impact.

Since 2013, the CPC central authorities have made dispatching anti-graft inspectors in teams to ministries, provincial governments, state-owned enterprises and public institutions a regular practice.

This year has seen three rounds of inspections, compared with two in 2013. The third round is under way at 13 state organizations, including the Ministry of Culture, China State Shipbuilding Corporation, China Unicom and Sinopec.

Inspectors report leads on possible graft to the CCDI after collecting information from local discipline inspectors and anti-graft agency officers, taking tips from the public and interviewing retired officials and former colleagues.

Although inspectors are not allowed to interrogate the officials in question, Wang Qishan, CCDI chief, confirmed that their work has led to the exposure of discipline violations and malpractice in promotion of officials.

All 31 provincial divisions, six state-owned enterprises and nine central government departments and public institutions are subject to these inspections.

To engage the public, attempts have been made to reduce the mystery surrounding anti-graft work and increase online interaction.

The CCDI website has launched an online tips service, publicized sanctions against corrupt officials, hosted online press conferences, opened forums and organized surveys.

Last month, TV footage on CCTV, the national broadcaster, first revealed how inspectors work in inspection rounds by showing two inspectors talking with Sinopec President Fu Yucheng.

The anti-graft campaign has also expanded overseas to cut off the escape route of corrupt officials.

Operation Fox Hunt, which will end on Dec. 31, has brought about 400 fugitives back to China, many of whom were corrupt officials, and 54 percent of them have turned themselves in.

On Tuesday, the CCDI solicited domestic and international tips about other corrupt officials still at large on foreign soil.

Prof. Ren Jianming, an expert on anti-corruption and governance with the Beijing University of Aeronautics and Astronautics, told Xinhua that these new initiatives have helped close loopholes in the Party and government systems and contributed to the long-term anti-graft battle.

Zheng Yongnian, a China studies expert with National University of Singapore, said that the anti-corruption drive is more than just netting "tigers and flies," but is also about giving reform opportunities to clean and honest officials.

"Rooting out corrupt officials and pushing forward reform measures are the ultimate purpose of the campaign," said Zheng.

In return, additional reforms will benefit the drive. A comprehensive legal reform plan, adopted at a key CPC session in October, included measures to push the Party, government, and officials to work in line with the law and build a more independent judicial system.

Zhou's case highlights a basic principle of rule of law, which holds that all people are equal before the law, Huang Weiting said.

Local legislatures have attempted to improve anti-corruption legislation. The legislature of Guangdong Province in south China has consulted the public about a draft provincial regulation on corruption prevention.

The bill has drawn nationwide attention because it is the first one to ban "naked officials" -- officials whose spouses and children have all emigrated -- from leading positions and other "important and sensitive" posts. "Naked officials" are considered a high-risk group for corruption and fleeing investigation.

Experts noted that legal reform will help push the anti-corruption drive and improve efficiency and legitimacy.