TOKYO, June 5 (Xinhua) -- The Tokyo head office and other facilities of Kobe Steel Ltd. were raided by police and prosecutors Tuesday over a protracted quality data fabrication scandal that has raised concern about the nation's manufacturing industry.

Along with its head office in Tokyo, Kobe Steel's headquarters in Kobe, Hyogo Prefecture and three of its manufacturing plants were also searched by police and prosecutors.

They suspect that the company, already embroiled in a data fabrication scandal, by intentionally misrepresenting its products, may have violated fair trade competition laws here.

"We are dealing seriously with the investigation," a public relations official of the company, was quoted as saying on Tuesday.

The embattled company has already admitted to falsifying inspection data on hundreds of aluminum and copper products for both the domestic and international market.

The company's own internal probe concluded in a final report issued in March that it had altered data related to the strength and other pertinent aspects of its products at a total of 23 of its plants in Japan and abroad.

It said the fraudulent practices were carried out so that its products appeared to meet their clients' specifications on aspects like tensile strength and durability.

Kobe Steel was founded in 1905 and has been a bastion of Japan's manufacturing sector.

The revelations and protracted nature of the data fabrication scandal, however, have cast doubts over corporate governance in the manufacturing industry and beyond in Japan, and cast serious aspersions over Japan's once stellar reputation for precision manufacturing, industry experts here said.