Nippon Broadcasting System Inc. said Tuesday that many advertisers have threatened to withdraw sponsorship of baseball and soccer game broadcasts if Internet company Livedoor Co. takes over its management.

NBS officials told a news conference that the radio broadcaster has been receiving such threats since it company became the target of a heated acquisition battle between Livedoor and Fuji Television Network Inc.

At the news conference, Nippon Broadcasting President Akinobu Kamebuchi emphasized that the value of his company would be damaged if Livedoor became its parent.

"Nippon Broadcasting has spent 10 to 20 years cultivating its knowhow and technology for radio broadcasting" of games, he said.

He criticized the way Livedoor obtained its large stake in NBS during off-hours trading on the Tokyo Stock Exchange in February.

"The conduct violated the original spirit of the securities law," he said. "I think it was an act of terrorism in the stock business."

He claimed that the company would have held talks with Livedoor if it had acquired NBS shares through a public tender offer.

Kamebuchi thanked NBS' shareholders for cooperating with Fuji TV's public tender offer. Earlier in the day, the TV broadcaster said its bid had been accepted and that it has secured a more than one-third stake in NBS.

"Nippon Broadcasting will remain in the Fujisankei group," Kamebuchi said.