A Japanese boy stabbed on his way to school in China died early Thursday, Japanese media reported, in an incident set to further inflame tensions.

A man attacked the 10-year-old in the southern Chinese city of Shenzhen on Wednesday morning and the child was rushed to hospital, the reports said.

It remains unclear whether the attacker intentionally targeted a Japanese national, Japan's Kyodo News reported.

In June, a Japanese mother and child were injured in another knife attack in Suzhou near Shanghai, Kyodo said. A Chinese woman died attempting to stop the assailant.

Japanese Foreign Minister Yoko Kamikawa said that the government "takes (the death of the boy) extremely seriously," media cited her as saying.

Late Wednesday, before the boy died, Japan's Vice Foreign Minister Masataka Okano summoned Chinese Ambassador to Japan Wu Jianghao to convey "serious concerns" over the attack.

Okana requested that "appropriate measures be taken from the perspective of preventing (any) recurrence, and strongly urged that security be strengthened including around Japanese schools throughout China, and that every effort be made to ensure the safety of Japanese nationals," Japan's foreign ministry said.

"In response, Ambassador Wu expressed that it was heartbreaking that such an incident had occurred, and said he would work to strengthen the safety of foreign nationals including Japanese nationals in China," the Japanese statement added.