TAIPEI -- Taiwan Semiconductor Manufacturing Co.'s most important plant for supplying Apple processors has been hit by a contamination of gas used in the chipmaking process, the company said on Friday.

The factory -- dubbed Fab 18 -- is the company's most advanced chipmaking facility. All of the latest processors for upcoming iPhones and Mac computers are produced there, industry sources told Nikkei Asia.

"Some gas supply in one of our plants in the southern Taiwanese city of Tainan seemed to be contaminated and the company immediately mobilized our other gas supplies to support it," the company told Nikkei. TSMC said it is closely monitoring the follow-up procedures to ensure production quality is uncompromised. The contamination was discovered on Thursday night, it said.

"As of now the incident does not have an obvious impact on the operation," TSMC said.

The contamination comes as Apple and its suppliers are finalizing components and preparing to begin final assembly for the latest iPhones and new Macs by the end of August.

Sources familiar with the matter said the gas contamination affected the chip manufacturing process in a limited way and TSMC immediately called employees who had gone home to return to the factory to control the situation.