SoftBank Corp. is suspending negotiations to acquire T-Mobile US Inc. through its subsidiary Sprint Corp. following difficulty gaining approval from regulators, who fear the merger would leave the market with too few major mobile carriers, SoftBank sources said Wednesday.

Although SoftBank will suspend the talks in the short run, there is still a possibility it may resume the negotiations in the future, according to the sources.

If the bid is dropped, Sprint, which was acquired by SoftBank last year, may have to shoulder a huge burden in investing in communications network infrastructure alone amid a slow business recovery.