No restart date was available, the spokesman said, declining to provide further details.

There was also no start date for the company's Sendai refinery, which shut down automatically as the quake struck nearby, the spokesman said, without providing more detail.

The 7.3-magnitude quake caused the shutdown of about a fifth of Japan's refining capacity, as well as injuries and some damage across a wide area of Japan.

Capacity is quickly being restored, though. Fuji Oil has restarted a refinery that was shut down automatically by the quake.

(Reporting by Aaron Sheldrick and Yuka Obayahishi; Editing by Kevin Liffey)

By Aaron Sheldrick and Yuka Obayashi