DESPERATE SEARCH

Japan Ground Self-Defense Force soldiers conduct search and rescue operations at an apartment which collapsed following an earthquake in Minamiaso town, Kumamoto prefecture, southern Japan, in this handout photo released by the Joint Staff of the Defence Ministry of Japan and taken April 17, 2016. [Photo/Agencies]

The Kumamoto region is an important manufacturing hub and home to Japan's only operating nuclear station.

Chief Cabinet Secretary Yoshihide Suga said the government would "take all the necessary measures" to support companies affected by the disaster and the economy more broadly, including tapping into reserve funds of 350 billion yen ($3.24 billion).

Abe said a sales tax increase next year would go ahead barring a financial crisis or major natural disaster, without elaborating on whether the quakes qualified as such a disaster.

On the stock market, Sony Corp and Toyota Motor led the sharp falls among manufacturers, dropping 6.8 percent and 4.8 percent respectively. Nissan Motor and Honda Motor both lost about 3 percent. Insurers and utilities were also sold, with nuclear plant operator Kyushu Electric Power slumping nearly 8 percent.

Toyota said it would suspend production at plants across Japan after the quakes disrupted its supply chain.

Electronics giant Sony said its Kumamoto image sensors plant would remain suspended. One of the company's major customers for the sensors is Apple. Honda said production at its motorcycle plant in southern Japan would remain suspended through Friday.

The Kumamoto government said 42 people had been killed and nine were missing.

Thirty three people have been confirmed dead in Saturday's quake and nine in the smaller tremor just over 24 hours earlier. The government said about 190 of the injured were in serious condition and some 110,000 people had been displaced.