HISAO KODACHI, Nikkei staff writer

TOKYO — As Japan tightens restrictions on overseas investors, the Finance Ministry looks to offer clarity by listing the sensitive companies for which foreign ownership will require government approval.

Foreign investors currently need to pass a government review before they can take a stake of 10% or more in certain Japanese companies.

Prime Minister Shinzo Abe’s government plans to lower the threshold to 1% as part of new investment regulations set to take effect as early as spring, citing national security concerns.

But the investment community expressed concern over ambiguity in the scope of the requirement.

The Finance Ministry said Friday it will place all of Japan’s publicly traded companies into one of three categories: (a) Companies such as weapons makers and nuclear power providers which will always require government approval, (b) those that will be exempt under certain circumstances, and (c) those that will never require review.

The ministry said the new rules “are not intended to shut out activist investors.” Some investors welcomed the list proposal, with one international asset manager saying it resolved some of the uncertainty surrounding the regulation.

But others worried it could hinder the dialogue between companies and their shareholders.

“If the government restricts foreign investment in certain companies to defend management control, it could be a major blow to governance at Japanese corporations,” said Shinichi Ichikawa, senior fellow at Pictet Asset Management (Japan).