AT&T's plans to acquire T-Mobile recieved a setback today when the U.S. Justice Department filed an antitrust complaint requesting that the deal be blocked, Bloomberg reported.

The controversial plan, which was announced in March, would result in AT&T paying $39 billion to acquire T-Mobile from its parent company Deutsche Telekom. AT&T touted the merger as a way to roll out Long Term Evolution (LTE) 4G networks to more customers and foster innovation. Some of its competitors and a few lawmakers have been more skeptical of the deal, while a group of customers have sued AT&T in an attempt to block the merger.

The Justice Department's complaint, filed in federal court today, says the merger would be a violation of U.S. antitrust law, a concern voiced by the aforementioned consumer-led lawsuit.

If it were to be approved, the merger would effectively result in a duopoly in the wireless industry, with AT&T and Verizon dominating the space and, some fear, leaving little room for competition and the interests of consumers.

"AT&T's elimination of T-Mobile as an independent, low- priced rival would remove a significant competitive force from the market," the U.S. filing said.