A knife-wielding man stabbed to death four primary school children in southern China on Friday, state media reported, the latest in a series of such attacks in recent years.

The stabbings occurred in the Guangxi Zhuang Autonomous Region in southern China, the official Xinhua news agency said, citing local authorities.

The attack took place in the town of Pingshan in Lingshan county as the students were on their way to school, the report added, citing the county public security bureau.

Three of the children died at the scene and the other died later in hospital, the report said.

Police are searching for the suspected assailant, described as middle-aged, the report said.

Chinese state TV reported on its verified account on China's Twitter-like Sina Weibo that a slightly heavyset 56-year-old man surnamed Shi residing in Pingshan rode a red motorised trishaw while stabbing the children.

Local police publicised the number plate of the trishaw and offered a reward of 20,000 yuan ($3,260) for information leading to the man's capture, it added.

Violent crime has been on the rise in China in recent decades as the nation's economy has boomed and the gap between rich and poor has expanded rapidly.

Studies have also described a rise in the prevalence of mental disorders, some of them linked to stress as the pace of life becomes faster and socialist support systems wither.

In early September, state media reported that a man stabbed three children and a teacher to death and wounded several others in a rampage at a primary school that refused to enrol his daughter.

That followed a March 2013 incident in which a man killed two relatives and then slashed 11 people, including six children, outside a school in China's commercial hub Shanghai.

2010 alone saw five attacks that killed 17 people -- 15 of them children -- and wounded more than 80.

A rise in incidents has forced authorities to increase security around schools and led to calls for more research into the root causes of such acts.

The Guangxi region, where Friday's attack occurred, was the scene in September 2012 of an attack in which a man wielding an axe killed three children and injured 13 others.

State media reported in January that the man, Wu Yechang, was sentenced to death for the attack and appealed but the motion was rejected by a higher court on Wednesday and now moves on to the Supreme Court.