A three-year-old Chinese boy died and a girl was seriously injured when a knife-wielding woman attacked the children on Sunday, media reported, the latest in a series of assaults against youngsters.

Police detained the suspect, who was aged about 40, and seized a kitchen knife and a dagger, Xinhua news agency said, adding that inquiries revealed she may be mentally ill.

The injured girl, who is aged nine, is being treated at hospital, it added, citing local authorities.

The report on the incident, in Beihai in southern Guangxi region, did not give details of any relationship between the woman and the victims.

The attack was the second to take place against children in Guangxi in recent weeks, after a man stabbed to death four pupils as they went to school in September. The victims were reported to have been aged under 12.

Earlier in September, a man stabbed to death three children and a teacher and wounded several others in a rampage at a primary school in central Hubei province.

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 noted a rise in the prevalence of mental disorders in China, with many failing to get proper treatment due to a lack of resources and qualified professionals.