Tokyo, Aug 14 (IANS): Japan's Fire and Disaster Management Agency said on Wednesday that 23 people died among 12,751 people who were rushed to hospitals due to heat-related illnesses across Japan over the week from August 5.

Amid a protracted heatwave that has scorched wide swathes of Japan, the agency's preliminary data showed that the number of people rushed to hospital due to the heat had risen past the 10,000 level for the second straight week, the Japan Times reported.

Of those rushed to hospital, the agency said that 400 of them had to be admitted for treatment of severe symptoms for at least three weeks. Shorter stays in hospital were required for around 4,500 patients, the agency also said.

Tokyo saw the highest number of people treated for heat-related conditions at 1,465, followed by the neighbouring prefecture of Saitama at 977 patients. Osaka, meanwhile, saw 897 people rushed to hospital for treatment due to the severe heat.

Of the total people requiring hospital treatment, around 55 per cent of them were aged 65 or older.

According to Japan's Meteorological Agency (JMA) on Wednesday, the highest recorded temperature anywhere in Japan this year was logged in Joetsu City, Niigata Prefecture on the western coast, where the mercury soared to 40.3 degrees Celsius.

Also in Niigata, Sanjo City saw temperatures hit 39.5 degrees Celsius.

Cities in Yamaguchi Prefecture, Tottori Prefecture and Hyogo Prefecture saw the mercury rise well over 37 degrees Celsius, the weather agency said.

The protracted heatwave is being caused by warm air from Typhoon Krosa, the 10th of the season, which may approach the western regions of Kyushu and Shikoku and cut path through western Japan on Thursday, sweeping across the archipelago and causing unsettled fronts particularly in regions facing the Sea of Japan, the JMA said.