China has executed a man for fatally stabbing a 10-year-old Japanese boy last September, the Japanese embassy in China has told the BBC.

Zhong Changchun was sentenced to death in January for attacking the boy, who had been walking to a Japanese school in south-eastern Chinese city of Shenzhen.

The case had sent shockwaves through both countries and fuelled diplomatic tensions amid allegations of it being a xenophobic attack.

“The Government of Japan considers the murder of a completely innocent child to be an unforgivable crime, and we take this execution with the utmost solemnity,” the Japanese embassy said in its statement to the BBC.

“In light of this incident, the Japanese government will continue to take all possible safety measures and strongly urge the Chinese side to ensure the safety of Japanese nationals in China.”

It said that it had been informed of the execution by the Chinese Ministry of Foreign Affairs.

The incident heightened fears among Japanese living in China and prompted Japanese companies including Toyota to ask their staff to take precautions. Others, like Panasonic, offered employees free flights home.

The verdict on Zhong’s case made no mention of Japan, Japanese officials previously said. Kenji Kanasugi, Japan’s ambassador to China said Zhong had requested to speak to the victim’s family, but did not say if he had been targeting Japanese nationals.

The incident has also shone a light on the unchecked nationalism on Chinese social media, which has fuelled anti-foreigner sentiment in recent years.

Online commentators noted that the schoolboy’s killing happened on a politically sensitive date – 18 September, the anniversary of an incident that led to the Japanese occupation of Manchuria in China in the early 1930s.

Historical grievances have long overshadowed political tensions between China and Japan. China has long demanded an apology from Japan for its colonial and wartime aggression in the early and mid 20 Century. It has also accused Japan of glossing over its brutal military actions in China in its history textbooks.

The stabbing also came amid a spate of high-profile attacks on foreigners in China, including the stabbing of four American teachers in Jilin.

Last June, a man attacked a Japanese mother and her child at a bus stop in Suzhou but ended up killing a Chinese woman trying to protect them. The man has also been executed, Japanese officials said last week.