China's fight against corruption has gained "crushing momentum" and huge progress has been achieved, with no let up expected next year, the ruling Communist Party said.

Since assuming office four years ago, President Xi Jinping has waged war on deep-seated graft, warning like others before him that the problem is so bad it could affect the party's grip on power.

Dozens of senior people have been jailed, including Zhou Yongkang, who was once China's powerful domestic security chief, given a life sentence for corruption last year.

"The battle against corruption has gained crushing momentum," state news agency Xinhua said late on Wednesday, in a report on a meeting of the party's Politburo chaired by Xi.

"Recent years have seen huge progress and improved public confidence in the campaign to strictly govern the Party and fight corruption," it added.

"In 2017 existing corruption should be reduced, and any rise in corruption contained."

A "high-voltage" crackdown to stem "undesirable work styles and corruption" must also be continued, Xinhua said.

The meeting of the Politburo, one of the party's ruling inner cores, set Jan. 6-8 for the next plenary session of the party's internal graft watchdog, the Central Commission for Discipline Inspection, the report added.

China does not have an independent anti-corruption body and insists the party and the government can police themselves, something some experts and Chinese activists say is not possible if the country really wants to tackle graft.

The drive for a corruption-free party, often referred to in official documents as "intra-party supervision", was the focus of a four-day meeting of senior party officials in Beijing in October, which concluded by anointing Xi as "core" leader of the party.