A minor fire broke out at Samsung SDI's factory in Tianjin, China early Wednesday, which started in a warehouse storing waste material.

The fire was extinguished by the fire department immediately and there were no casualties. Operations were unaffected and the situation has returned to normal, the company said.

Samsung China told local media that the precise cause was still under investigation and denied that it was caused by lithium batteries.

Tianjin fire department said 19 fire trucks and 110 personnel were sent to extinguish the fire in its Sino Weibo account but the post has since been deleted.

Samsung SDI, along with China's ATL, were the battery suppliers for the ill-fated Galaxy Note 7 made by Samsung Electronics. Samsung said batches from both suppliers had defects that caused fires.

Samsung SDI is expected to supply the main battery batches for the upcoming Galaxy S8.