China expressed grief on Thursday over the passing of a Japanese boy who was fatally stabbed near his school in Shenzhen, Guangdong province, reiterating that it was an isolated case.

Calling it an unfortunate incident, Foreign Ministry spokesman Lin Jian said that "we mourn the passing of the boy and express our condolences to his family".

Lin revealed that the boy was a Japanese national, and that his father is a Japanese citizen and his mother a Chinese citizen.

It was reported that the student was on his way to school on Wednesday, accompanied by one of his parents, when he was stabbed in the abdomen by a knife-wielding man. The motivation of the attacker was not known.

The boy was immediately sent to a hospital, and Guangdong sent medical experts who made all-out efforts to try to save his life, Lin told a daily news conference.

The Chinese side will provide necessary assistance to the boy's family in handling the aftermath, he said, stressing that the case is still under investigation and relevant Chinese authorities will handle it in accordance with the law.

China and Japan are in communication on the case, he added.

In a statement released on Wednesday, Shenzhen police said that a 44-year-old man surnamed Zhong had been taken into custody.

China upholds the rule of law and the Chinese government brooks no illegal or violent activities, Lin said, adding that relevant authorities will bring the criminal to justice in accordance with the law.

Lin emphasized that this was an isolated incident and similar cases could happen in any country, saying that he believes that it will not affect exchanges between China and Japan.

"China has always taken, and will continue to take, effective measures to ensure the safety of all foreign nationals in China."

He said that China always welcomes people from all countries, including Japan, to visit, study, do business and live in China.