TOKYO, March 14 (Reuters) - Japanese oil refiner Idemitsu Kosan Co has shut all units at its 120,000 barrels-per-day Tokuyama refinery complex in western Japan after a strong earthquake, the company said on Friday.
An earthquake of magnitude 6.3 struck off Japan's southern island of Kyushu near the city of Oita, the U.S. Geological Survey said.
Naphtha crackers at the Tokuyama plant with the capacity to produce 687,000 tonnes of ethylene a year were also shut down, a company spokeswoman said, adding that it was unclear when operations would resume.
Idemitsu's ethylene units caught fire more than two hours after the quake, but the fire was put out soon after, the company said.
The earthquake did not hit the operations of other refineries in western Japan run by JX Nippon Oil & Energy , Cosmo Oil Co, Taiyo Oil Co, and Seibu Oil Co, which is a part of the Showa Shell Sekiyu group.
There was no impact to naphtha crackers run by Showa Denko and Asahi Kasei, company spokespeople said.
Mitsubishi Chemical Corp reported no impact to its Mizushima naphtha cracker, but shut three polyethylene units at the complex there, with operations expected to return to normal later in the day. (Reporting by Osamu Tsukimori; Editing by Paul Tait and Clarence Fernandez)