(Adds plant shutdown, power failure details)
TOKYO, Jan 17 (Reuters) - Nippon Steel & Sumitomo Metal Corp's entire Nagoya steel plant in central Japan was shut after smoke and flames were seen billing out of one of the plant's units earlier on Friday.
Just before noon local time (0300 GMT) a power failure occurred at the plant, which was followed by flames and smoke seen escaping from a coke oven, a company spokesman said, adding it came from a process to burn off gas accumulated during regular operations and not an outbreak of fire.
An official at the local fire department said fire engines were sent to the site around 12:30 p.m.
Nippon Steel is gathering information about the incident and there is no estimate for when plant, which produced 6.46 million tonnes of crude steel in the year to March 2013, will return to operations.
No injuries were reported from the incident.
Shares in Nippon Steel finished down 1.5 percent on the day, versus an 0.1 percent dip in the Nikkei stock benchmark.
(Reporting by Nobuhiro Kubo, Emi Emoto, James; Writing by Chang-Ran Kim; Editing by Shinichi Saoshiro and Matt Driskill)