BEIJING (REUTERS) - China's main anti-corruption watchdog has punished four of its own officials for incidents ranging from beatings to drunk driving, state media said on Monday, underscoring Beijing's challenge to stamp out deep-rooted graft and illegal activity.

President Xi Jinping launched a crackdown on corruption soon after becoming head of the ruling Communist Party in late 2012, seeking to win back public confidence in the face of a seemingly endless stream of embarrassing scandals.

The party warned last week that its own officials were often complicit in corruption cover-ups.

The official Xinhua news agency said the four graft-busters, who worked for the party's Central Commission for Discipline Inspection, had received punishments ranging from dismissal to criminal prosecution.

In the most serious case, Wu Qiang from southern Jiangxi province, was expelled from the party and handed over for prosecution for killing a pedestrian while drunk driving and then fleeing from the scene, Xinhua said.

In another incident, Wu Jimian from central Hubei province was prosecuted for striking and killing a hotel worker while driving a police car after leaving a banquet, the report said.

Shen Wanhao, from northern Hebei province, was sacked after he beat up another corruption fighter at an official banquet, Xinhua added.

A fourth official, Ren Jiangang, from northern Shanxi province, received a party warning for holding banquets to commemorate his father's death, the report said.

Like others before him, Mr Xi has warned that graft is such a serious problem it threatens the party's very survival, and has vowed to go after powerful "tigers" as well as lowly "flies".

The government has sought to curtail everything from bribery and gift-giving to lavish banquets, aiming to assuage public anger over graft and extravagance by some officials.