AT&T's fight with Sprint Nextel over its right to buy T-Mobile USA keeps getting uglier.

The latest move by AT&T: claiming Sprint is two-faced, pointing out contradictions between its publicly made arguments and its confidential responses to the Federal Communications Commission. AT&T won the right to access Sprint's confidential documents because it needs to prepare for its defense against the Department of Justice. AT&T filed a document pointing out the difference in opinion to the FCC.

The war of words has gotten increasingly bitter, as AT&T scrambles to save its deal with T-Mobile. The telecommunications giant still needs to face off against the Justice Department, which has sued to block the deal. While the Justice Department case remains the primary hurdle, Sprint and regional carrier C Spire have also drafted behind the suit with their own legal actions.

Today's move marks the latest tactic by AT&T to undermine Sprint's case. Sprint has been largest standard bearer opposing the deal. The company was dismissive of the claim.

"AT&T's latest FCC filing is an attempt to distract the public and the media from the weakness of its case and the strong opposition to its proposed takeover of T-Mobile," Sprint spokesman John Taylor said.

Sprint made its own filing to the FCC last month, spelling out the discrepancies between AT&T's comments to regulators and to investors, including AT&T's claim to D.C. that the merger will create jobs, while its comments to investors suggest work force reductions.

Not only is AT&T's proposed transaction being challenged in Federal Court by the U.S. Department of Justice, a bipartisan group of eight state attorneys general, and C Spire Wireless, but it's also opposed at the FCC by numerous other wireless carriers, consumer advocates, public-interest groups, and businesses, not to mention tens of thousands of individual consumers, all of whom have come to the same conclusion: AT&T's proposed takeover of T-Mobile will hurt consumers, harm competition, and diminish the innovation that's been the hallmark of the wireless industry."

Sprint has publicly claimed that AT&T faces no spectrum crisis, and that AT&T's acquisition of T-Mobile would give the combined company too much spectrum, produce few merger-related cost cuts, and hurt its independent existence. In addition, the powerful duo of AT&T and Verizon Wireless has kept the best handsets from coming to Sprint.

AT&T, however, said Sprint's confidential submissions show that Sprint agrees with the assessment that mergers between wireless providers can create "immense synergies." It also says Sprint holds the strongest spectrum position out of any U.S. provider and has a growing strategic advantage in the industry. It also says Sprint concedes that AT&T faces major spectrum constraints. Lastly, it said Sprint admitted that it wasn't at a disadvantage when it comes to accessing new handsets.

On T-Mobile, the documents acknowledge that the carrier is a struggling competitor with no clear path to 4G and is not a leader in innovation.

These comments, which AT&T says illustrate Sprint's own self-interests in opposing the deal, are taken from a larger part of a confidential document.

"Sprint opposes this acquisition not because it would harm consumers, but precisely because it would benefit consumers by giving them a more efficient alternative to Sprint," AT&T said in the filing.

Updated at 10:15 a.m. and 10:52 a.m. PT to include a comment from Sprint.