The quality control scandal at Japan's Kobe Steel got worse after the company admitted one of its copper plants was under investigation for breaching Japan's industrial standards.

Inspectors with Japan's Quality Assurance Organization are now scrutinizing copper pipes produced at a Kobe Steel plant in Hadano, a city west of Yokohama.  These pipes are used in plumbing and air conditioning systems.

Kobe is one of Japan's largest producers of steel and aluminum used by auto-makers, aerospace companies, and train builders.  Earlier this month, it announced that it had faked safety data for many of its products and shipped them off to 500 companies where safety is vital:  Automakers, train and aircraft producers, and makers of electronics and other equipment. 

The episode has caused supply chain difficulties with the companies that received those items.  The Wall Street Journal reported that those customers were forced to scramble to inspect their finished goods for any flaws.  So far, none have found safety issues associated with the products.