Nintendo Co. said Thursday its group operating profit for the six months to Sept. 30 dived 51.0 percent on smaller sales of its GameCube video console and ballooning development costs for its next-generation Revolution console.

In its earnings report for the first half of the 2005 business year, Nintendo said the profit from its core business lines slumped to 19.61 billion yen due to flagging sales of both the hardware and software of the GameCube console, for which four years had passed since its debut.

Sales at the rival of the Sony Computer Entertainment Inc. and Microsoft Corp. console business fell 6.2 percent to 176.36 billion yen, with net profit dropping 21.1 percent to 36.63 billion yen.

Nintendo's net profit per share in the fiscal first half slipped to 282.34 yen from 349.00 yen a year earlier.

For the full year to next March 31, Nintendo forecast its group pretax will amount to 125 billion yen and net profit 75 billion yen on projected sales of 500 billion yen.