China on Thursday expressed regret and sadness after a Japanese schoolboy was stabbed to death in Shenzhen.

"China expresses its regret and sadness that this kind of unfortunate incident occurred," Foreign Ministry spokesman Lin Jian said.

"We mourn the passing of the boy and express our condolences to his family."

Lin described the attack as an isolated case.

The boy, 10, was on his way to the Shenzhen Japanese School on Wednesday when he came under attack about 200 metres from the gate.

He died later in hospital.

A suspect, 44, was arrested at the scene.

The victim's father is a Japanese citizen while his mother is a Chinese citizen.

"China will provide all necessary assistance to his parents in the aftermath," Lin said.

An investigation had been launched and "China and Japan are in communication on the case," he added.

Japanese Prime Minister Fumio Kishida called the attack "extremely despicable".

"For now, we will strongly urge China to provide an explanation about the facts of what happened," he said.

"Since it's been more than a day since the incident happened, we expect them to offer an explanation as soon as possible."

Japanese Foreign Minister Yoko Kamikawa said she'd instructed Japanese schools in China to review their safety measures.

The Foreign Ministry has said China will continue to take effective measures to protect the safety of all foreigners in the country. (Agencies)