Livedoor Co.'s stake in Nippon Broadcasting System Inc. slightly surpassed 50 percent as of late last month, a Finance Ministry office said Friday.

A report submitted by Livedoor to the Finance Ministry's Kanto Local Finance Bureau showed the fast-growing Internet service provider had obtained about 16.4 million out of 32.8 million outstanding NBS shares as of March 25.

By obtaining a majority of all outstanding shares in the radio broadcaster, it has become certain that Livedoor will take control of the firm's management.

The number of shares Livedoor reported as its shareholdings include those it purchased through margin trading. On the assumption that Livedoor paid all the money for the margin deal, the company has secured a 53.83 percent stake in NBS' shares with voting rights, based on the list of shareholders as of the end of last September.

Livedoor has been battling Fuji Television Network Inc. for control of the radio station since early February. Both NBS and Fuji TV are core members of the Fujisankei Communications Group.

Meanwhile, NBS said Thursday three of its external board members have stepped down due to "personal reasons," reducing the number of its board members to 16 ahead of the company's general shareholders' meeting in June.

Some observers said the three -- Hiroaki Eto, adviser to Mizuho Trust & Banking Co., lawyer Hideaki Kubori and freelance journalist Tomoyo Nonaka -- might have resigned due to Livedoor's acquisition of a majority stake in NBS.