The Diet on Wednesday approved legislation to prevent foreign companies from gaining control of domestic broadcasters by using affiliates in Japan, paving the way for its implementation next spring.

The measure to revise the radio and broadcast laws was enacted after it cleared the House of Councilors on Wednesday.

Under the revised laws, the government will limit to less than 20 percent the combined stake that a foreign company can directly or indirectly hold in a Japanese broadcaster in terms of voting rights.

Current laws limit foreign investors or firms to direct stakes of less than 20 percent, but they don't limit the size of equity stakes they can own via affiliates.

The revisions add Japanese affiliates in which foreign investors or foreign firms are invested to the category of investors that can be regulated by the laws.

The revisions were worked out hastily in the wake of Livedoor Co.'s attempt earlier this year to take over Nippon Broadcasting System Inc., an AM radio broadcaster that was the biggest shareholder in Fuji Television Network Inc.

The Internet services company had issued convertible bonds to U.S. investment bank Lehman Brothers to help fund the acquisition of Nippon Broadcasting.

If Lehman converted all the bonds into Livedoor shares, it would be a major shareholder of the Internet services company, raising the possibility it would indirectly control the radio station and possibly influence Fuji TV if Livedoor had succeeded with the bid.