Son was speaking at an annual shareholders' meeting, ahead of a gathering of Sprint shareholders next Tuesday to vote on SoftBank's offer.

Sprint moved on Thursday to take the upper hand in another battle with Dish over control of Clearwire Corp, raising its buyout offer to $5 per share, which it said had helped to win support from a key group of dissident shareholders.

Sprint had already bought a majority stake in Clearwire, which both Sprint and Dish were eyeing for its wireless airwaves that they hope to use for their networks.

(Reporting by Mari Saito; Writing by Sophie Knight; Editing by Edmund Klamann)