TOKYO - Japan's Softbank said Thursday net profit jumped nearly three-fold in the six months to September on strong sales of the iPhone and gains from selling holdings in US Internet firm Yahoo!.

Group net profit rose 182.7 per cent from a year earlier to 217.3 billion yen (S$3.6 billion) with operating profit growing 18.3 per cent to 373.2 billion yen, said the major Internet investor and mobile carrier.

Sales rose 4.8 per cent to 1.54 trillion yen on robust mobile business.

"Subscriptions grew smoothly in the mobile business and telecom revenue rose," the company said in a statement, noting sales were particularly strong for the iPhone and other smartphones.

Net profit also surged because of extraordinary gains, including 76.43 billion yen of proceeds for the sale of the bulk of its holdings in Yahoo! Inc. of the United States to repay a loan.

Softbank, Japan's third-largest mobile carrier by subscribers, now faces tougher competition in selling the iPhone.

Its exclusive deal to provide Apple's popular handset in Japan ended when bigger rival KDDI struck a deal to also sell it.