A top transplant specialist has undergone emergency surgery after being stabbed in his office on Thursday at a hospital in Nanjing, capital of Jiangsu province.

Sun Beicheng, head of Jiangsu Province Hospital's liver transplant unit, was stabbed in his left leg and suffered a fractured jaw and mouth lacerations in the attack, which happened at about 8:30 am.

The hospital said the doctor received immediate medical treatment and is in stable condition.

Increased numbers of security workers have been put on patrol to ensure the safety of medical staff, while services have been provided to hospital workers to help ease stress, the hospital said.

A doctor surnamed Chen said the suspect, a young man, entered Sun's office and locked the door. "Colleagues had to break in to save Sun after hearing strange noises, which sounded like someone struggling. There was a lot of blood in the office," he said.

Sun, who returned to China from the United States in 2004, has conducted 250 liver transplant operations and 1,500 liver resection surgeries.

According to the hospital, Sun often gives patients his cellphone number, telling them to call him if they experience problems concerning their transplant.

Police in Nanjing's Gulou district have detained a suspect, but said he was not a patient or a relative of any patient of Sun's. An investigation into the motive of the attack is underway.

Police said it was an isolated incident, but others referred to it as the latest in a string of attacks on medical workers.

In May, Chen Zhongwei, a dentist in Guangzhou, capital of Guangdong province, died in a hospital after being stabbed 38 times by a former patient.

In June, the 10-year-old son of a medical worker at Yuejiaqiao Health Center was stabbed by a man in Yiyang, Hunan province. The worker had previously treated the attacker for emphysema.

In July, a man in Hebei province stabbed a doctor to death with a jackknife, blaming him for his leg infection. The doctor had treated him 13 years earlier after he was injured in a car accident and lost the full use of his leg following treatment.

A survey conducted last year by Beijing News, the National Health and Family Planning Commission and the National Bureau of Statistics showed that only one-sixth of the 600,000 Chinese mainland citizens who obtained qualifications to practice medicine from 2010 to 2014 gained employment as medical workers.