A crackdown has been launched against organized groups that attempt to blackmail hospitals, threaten medical workers or try to profit from the grievances of the vulnerable.

The crackdown, launched on Sunday, will last until the end of March, said Sun Haibo, an officer from the public security management bureau under the Ministry of Public Security.

Hospitals have seen a spate of violent incidents recently. Besides attacks on medical workers, many hospitals also face a growing number of protests instigated by groups, including organized crime groups, which try to disrupt or threaten their work for financial gain.

The police are currently gathering evidence, analyzing data and preparing to take action across the country, Sun said.

Hospitals in northern and eastern areas, including Heilongjiang province, Hebei province, Beijing and Zhejiang province are particularly at risk as they each receive thousand of visitors every day, he said.

"Organized crime is often involved," Sun said. "Sometimes, a common medical dispute will escalate into something far more serious."

One female doctor, surnamed Wang, from Beijing Chaoyang Hospital, said "agent provocateurs" often roamed hospital corridors looking to sign up clients, who were often in a state of grief or otherwise emotionally vulnerable.

A typical scenario could be when a patient or family has a legitimate dispute with a hospital over fees. They may be approached by someone offering to "sort it out" by causing a scene or disrupting hospital work. With thousands of patients to care for, the hospital authorities could decide to waive any fees or take other action to end the disruption.

Those who caused the disruption then charge the patient or family an extortionate fee.

Unemployed men and farmers are often used to create such disturbances, by shouting slogans or playing loud sad songs, to disrupt the hospital's work, the doctor said.

Because of their busy schedules, doctors often have to ask patients to wait for hours before they can be seen and this can lead to a sense of frustration.

Li Lei, a 45-year-old Beijing shop clerk who has suffered from heart disease for five years, said each time he goes to a hospital for treatment he has to wait up to four hours to see a doctor.

"But then the doctor just gives each patient two or three minutes, is impatient and bad-tempered," he said.

"Doctors seem to be going through their paces, not paying any attention to us and then prescribing expensive drugs and not answering our questions."

He said patients had few channels to express frustrations. Doctors, too, feel badly treated.

"We are trying to help but we often have to deal with abusive language and violence from patients or their families," said Zhu Jihong, director of emergency calls, who has been working at the Peking University People's Hospital for 30 years.

"We feel helpless and hope law enforcement agencies will severely punish those who instigate disruptions," he said.