Japan's industrial output in January declined 7.5 percent from the previous month, the biggest fall since May 2020, as automobile production plunged amid suspensions at Toyota Motor Corp. group companies due to safety test scandals, government data showed Thursday.

The industry ministry revised down its basic assessment for the first time in six months, saying industrial output "showed weakness while fluctuating indecisively." It said last month that production in December was "fluctuating indecisively."

The decline was the largest since the 8.0 percent drop seen in May 2020, when production was affected by the coronavirus pandemic, according to the Ministry of Economy, Trade and Industry.

The seasonally adjusted index of production at factories and mines stood at 97.6 against the 2020 base of 100, the ministry said in a preliminary report. It followed a 1.4 percent expansion in December.

All 15 sectors except transport equipment, excluding motor vehicles, reported reduced production, with output in the automobile industry dropping 17.8 percent.

Output of electrical machinery and information and communication electronics equipment, including lithium-ion batteries used in automobiles, fell 8.3 percent, while general-purpose and business-oriented machinery sank 12.6 percent.

A ministry official attributed the sharp decline in overall production to output halts at Toyota Motor group companies Daihatsu Motor Co. and Toyota Industries Corp. following a series of safety test scandals.

Heavy snowfall during the reporting month also led to production halts among some manufacturers, due partly to difficulties in procuring parts, the official said.

Koichi Fujishiro, a senior economist at the Dai-ichi Life Research Institute, said the setback is likely to be temporary, as demand remains strong at home and abroad.

"Output is likely to pick up in the near future," he said.

In January, the index of industrial shipments dropped 8.3 percent to 96.2 for the first decline in two months, while that of inventories fell 1.8 percent to 101.0.

Based on a poll of manufacturers, the ministry expects production to expand 4.8 percent in February and climb 2.0 percent in March.

But the ministry official pointed out the importance of continuing to monitor the effects of a magnitude-7.6 earthquake that struck central Japan on New Year's Day, despite its limited impact in January.

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