China's urban management officers, or chengguan, have become infamous for abuse of power and assaults on street vendors. That negative reputation has recently been exacerbated by a video capturing their brutal tactics in the city of Yan'an, Shaanxi province.

In the video, which quickly went viral, a group of officers are seen trying to confiscate a shop owner's bicycles. As the incident heats up, one of the officers named Ding Jingwen jumps up and stomps on the owner's head.

Six of the temporary chengguan, including Ding, were fired by the local urban management bureau, while two other full-time employees were only penalized - a move that stirred another round of criticism, as many accused the authorities of passing the buck by blaming contract employees.

Chengguan were created in the 1990s as a low-level urban security force, separate from police, to deal with noncriminal administrative concerns such as noise control, parking and sanitation.

They have long been controversial, however, and cases of assaults by chengguan officers continue to make the headlines. In cases of foul play, authorities often claim that the perpetrators are "temporary" employees, not official civil servants permanently employed by the government.

On April 13, 2010, a villager in Hebei province's Zhuozhou city fell into a river and died while being chased by four "temporary" workers from an urban management bureau.

On June 24 the same year, a 4-year-old child was hit by a car belonging to the local urban management bureau, which turned out to be driven by a "temporary" worker, therefore the bureau denied responsibility.

Wu Jiang, head of the Chinese Academy of Personnel Science, says temporary employees are common in administrative government departments, especially in urban management.

As many as 88 percent of the officers in the urban management department in Huaiyin district of Huai'an, Jiangsu province, are working on short-term contracts, according to official figures.

Hou Shihuai, secretary of the Party committee of the Yan'an Urban Management Bureau, says his quota of certified employees is far less than the manpower needed.

Only 139 certified employees are insufficient to carry out urban management tasks in Yan'an, a city with a population of 600,000, so many chengguan are hired as temporary employees, says Hou. "But they have very heavy workloads, and seldom have time to study or train," he adds.

Yet some Chengguan officers in Yan'an have said that words are of little use when dealing with street vendors, so when verbal persuasion fails, they simply resort to violence.

Such behavior has created a dilemma: on the one hand, urban management officers have contributed to the overall development of many cities; on the other, periodic controversies regarding violent incidents by chengguan undermine the department's image.

Zhu Lijia, a public management professor at the Chinese Academy of Governance, says that while hiring temporary employees is common for government agencies, the institutions should still be held accountable when lapses occur during law enforcement.

"The agencies should train and manage their officers better, even if they are temporary."