Photo/Illutration A man cools himself with a folding fan while riding a train in Tokyo on June 27. The government warned of possible power shortages as the country endures an unusually intense heat wave. (AP Photo)

A fire caused Japan’s biggest power generator JERA to shut down a 500 megawatt unit at its Chiba thermal power station near Tokyo on Saturday, raising fears of an electricity crunch as a prolonged heatwave keeps demand at high levels.

The fire broke out around noon near the steam valve of one of the three turbines at the No.3 unit of the gas-fired combined-cycle power station, JERA said. The fire was extinguished about an hour later, it added.

JERA, a joint venture between Tokyo Electric Power Co. and Chubu Electric Power Co., was checking all equipment at the unit which had the fire said it would announce the timing of the restart when it is set.

Japan’s industry ministry has said energy supplies are expected to remain tight during the peak summer season. It has asked households and businesses to conserve electricity.

Authorities issued a daily warning about possible power shortages from Monday through Thursday last week as the country suffered its worst June heat since record-keeping began 147 years ago.

Any further unexpected disruptions in power generation may prompt renewed warnings.

On Sunday, central Tokyo marked its ninth straight day of temperatures above 35 degrees, reportedly the longest streak since record-keeping began in 1875.