Leap Wireless, a San Diego-based wireless communications company, has joined the growing chorus of opposition to AT&T's acquisition of T-Mobile USA.

The $39 billion deal, which would create the largest single wireless company in the U.S., has come under heavy scrutiny since it was first announced in March.

In a statement yesterday, the company said the merger would reduce the amount of competition in the wireless market and leave it dominated by AT&T and Verizon. The acquisition would harm consumers. It would reduce competition and decrease innovation and investment in the wireless industry. It would also accelerate the trend of alarming concentration of wireless providers and would eliminate T-Mobile as a competitive force that helps balance the increasing power of the largest carriers, the statement said.

The House Judiciary Committee is scheduled to hold hearings tomorrow to discuss the deal. The Department of Justice has to approve the merger, which has to pass muster with antitrust authorities.

Other companies that have opposed the merger are Sprint Nextel and MetroPCS. Sprint has also expressed concerns about the effect on competition, while MetroPCS has said that the amount of wireless spectrum AT&T would gain would be too great, concentrating it in too few hands.

Sprint Nextel has even approached state regulators in an effort to block the acquisition. Even though the Federal Communications Commission and other federal agencies have a large say in whether the merger happens, it must also be approved by state-level public utilities commissions. Sprint has registered its opposition in West Virginia and plans to do so in several other states as well.