UPDATE 2-Subaru says improper inspections conducted for over 30 years

* About 255,000 Subaru vehicles could be recalled

* Revelation follows govt-ordered internal investigation

* Subaru shares close down 2.6 pct (Recasts with announcement)

TOKYO, Oct 27 (Reuters) - Subaru Corp said on Friday it had failed to follow proper inspection procedures for vehicles destined for the domestic market for more than 30 years, adding to a list of compliance problems at Japanese companies.

The automaker said it had allowed uncertified technicians to conduct final inspections of new vehicles at its main Gunma factory complex, north of Tokyo, which violates requirements set by Japan's transport ministry.

As a result it is considering recalling around 255,000 vehicles produced at the complex, the maker of the Legacy and Forester said.

Subaru said it would report details of an internal investigation to the transport ministry on Monday.

"The final inspection process is very important and we acknowledge that we did not meet requirements," Chief Executive Yasuyuki Yoshinaga told a news conference.

"We used the same process for more than 30 years without realising that it did not meet ministry requirements."

The revelation follows a similar issue at Nissan Motor Co while Kobe Steel Ltd has been grappling with a data fabrication scandal, tarnishing Japan Inc's reputation for strict quality control.

Japan's transport ministry instructed domestic automakers to conduct internal investigations after Nissan late last month revealed violations on inspections governing vehicles sold in Japan at its domestic factories.

Nissan has recalled 1.2 million vehicles, including all passenger cars it produced for sale in Japan over the past three years, and suspended production of cars for the domestic market at its Japanese plants.

The ministry had set an end-October deadline for submitting the results.

Toyota Motor Corp and Honda Motor Co have reported to the ministry that they found no issues with their respective inspections, the two companies said on Friday.

Shares of Subaru closed down 2.6 percent on Friday after falling more than 3 percent following media reports of the improper inspections. The broader market rose 1.2 percent . (Reporting by Maki Shiraki; Writing by Chang-Ran Kim and Chris Gallagher; Editing by Christopher Cushing)