JAPAN'S SoftBank has cleared a major hurdle in its attempt to buy US wireless provider Sprint Nextel, as rival bidder Dish Network declined to make a new offer after SoftBank sweetened its own bid last week.

SoftBank Chief Executive Masayoshi Son is now a step closer to sealing the largest overseas acquisition by a Japanese company in history, after winning support from a key shareholder by raising SoftBank's offer to US$21.6 billion from US$20.1 billion last week.

Son, a rare risk-taker in a cautious Japanese corporate environment, has been determined to thwart a rival bid from Dish - led by Chairman Charlie Ergen, known for aggressive takeover attempts - in an effort to break into the US market.

"We look forward to receiving the FCC (Federal Communications Commission) and shareholder approvals which will allow us to close in early July and begin the hard work of building the new Sprint into a meaningful third competitor in the US market," SoftBank said in a statement.

SoftBank, one of Japan's top mobile operators, has promised that Sprint would be able to save money on equipment such as smartphones by getting bulk-buy discounts from vendors. It can also lend its expertise in wireless technology.

"The advantage of SoftBank is really about the synergy between the two firms ... in distribution, branding and retailing," said Hiroshi Yamashina, a senior telecommunications analyst at BNP Paribas in Tokyo.