Japanese telecoms company Softbank Corp said on Monday it aims to take a stake of up to 70 percent in U.S. carrier Sprint Nextel Corp in a deal that could be worth up to $20.1 billion.

The deal, which had been predicted by sources, gives Softbank access to a major overseas market as cutthroat competition in Japan limits profits at home, while Sprint will gain ammunition to potentially acquire peers and build its 4G network to compete better in a U.S. wireless market.

(Reporting by Mayumi Negishi and Junko Fujita; Writing by James Topham; Editing by Michael Watson)