Shinichi Nishimiya (C) pictured in 2005 at a meeting of the  Association of Southeast Asian Nations (ASEAN).

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Japanese Foreign Ministry confirms Shinichi Nishimiya, 60, died on Sunday

Nishimiya was due to replace the current Japanese envoy in Beijing -- Uichiro Niwa

His death comes amid worsening relations between China and Japan

Both countries claim sovereignty over a group of islands in the East China Sea

Hong Kong CNN  — 

The newly appointed Japanese ambassador to China has died after taking ill and collapsing in Tokyo late last week.

In a brief statement, the Japanese Foreign Ministry confirmed Shinichi Nishimiya, 60, died on Sunday after spending the weekend in hospital because of his “health condition.” He collapsed just two days after being appointed to the job.

The ministry did not disclose any further details about what had happened.

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Previously a deputy minister for foreign affairs, Nishimiya was due to replace the current Japanese envoy in Beijing, 72-year-old Uichiro Niwa, in the coming weeks amid heightened tensions between Japan and China.

The Japanese government’s recent purchase of a set of disputed islands in the East China Sea from a private owner has angered Beijing, which has called the acquisition “illegal and invalid.”

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On Friday China sent six surveillance vessels to carry out patrols around the remote islands, which Japan calls Senkaku and China calls Diaoyu, in an effort to underscore its claim to sovereignty. The ships briefly entered Japanese territorial waters despite warnings not to do so, the Japanese Coast Guard said.

The dispute also hit a nerve with many ordinary Chinese, as tens of thousands took to the streets at the weekend to protest against Japan’s stance. In Beijing, Japan’s embassy was attacked with eggs and bottles, while angry mobs in other cities across China ransacked Japanese businesses and burned Japanese-made cars.

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Though Japanese officials have sought to play down the significance of the deal to buy the islands, the dispute has come to represent what many Chinese people see as unfinished business: redressing the impact of the Japanese occupation of large swathes of eastern China during the 1930s and 1940s.

China says its claim goes back hundreds of years. Japan says it saw no trace of Chinese control of the islands in an 1885 survey, so formally recognized them as Japanese sovereign territory in 1895.

Japan then sold the islands in 1932 to descendants of the original settlers. The Japanese surrender at the end of World War II in 1945 only served to cloud the issue further.

The islands were administered by the U.S. occupation force after the war. But in 1972, Washington returned them to Japan as part of its withdrawal from Okinawa.

CNN’s Junko Ogura contributed to this report.