TOKYO -- More than 9,400 residents were ordered to evacuate their homes on Tuesday after a fire broke out at a chemical plant in southwestern Japan, officials said.

The fire started at a plant run by Asahi Kasei Corp., a Japanese chemical firm, at around 5:15 p.m. (0815 GMT) in Nobeoka, Miyazaki prefecture, some 850 kilometers (527 miles) southwest of Tokyo.

"We issued an evacuation warning to a total of 9,407 people living near the plant as there is a possibility that toxic gas could be released from the plant due to the fire," said an official of Nobeoka City Hall, AFP reported.

"We have not received any reports of injuries," the official said, adding that some 540 people have moved to nearby shelters.

Asahi Kasei said some 40 cases containing cobalt, a minor radioactive material, were stored at the plant.

"But radioactive levels of the material are extremely low," said a spokesman for Asahi Kasei.

"Even if the cases were burnt and radiation leaked, it would not affect human bodies," the spokesman said.

The city set up an emergency office as the fire continued to burn late Tuesday.

"We had temporarily suspended fire-extinguishing operations on fears of possible explosions," the official said. "But we have now resumed firefighting work."