WASHINGTON (Reuters) - AT&T Inc complained on Wednesday that the Justice Department was too slow in telling who its witnesses would be as the government seeks to block the telecommunications giant's acquisition of rival T-Mobile USA.

The government, in a court filing Wednesday, proposed giving AT&T an initial list of up to 15 witnesses on November 18 and additional lists in December and January. The trial begins on February 13.

This did not please AT&T, which noted that the court had initially urged witness lists be exchanged "at the earliest possible time."

"More than six weeks after the court's order, defendants are still no closer to receiving a witness list. Yet plaintiffs seek to push the date back still further," AT&T said in its filing.

Instead, AT&T suggested Special Master Richard Levie consider giving each side a specific amount of time during the trial to be used as each side wishes.

"Plaintiff's (the government) case is likely to focus on the few competitors that plaintiffs claim matter in the market. Defendants' (AT&T) case will broaden that focus to show the much broader array of market participants competing fiercely for customers," AT&T said.

The government, for its part, argued that AT&T's desire for a quick trial would be undermined by its failure to cap its witness list.

"Defendants' proposal presages well over 100 depositions in December and early January. That is unreasonable, and court intervention now is necessary to stop it," the Justice Department said.

The Justice Department's antitrust division filed its lawsuit on August 31 to stop AT&T's acquisition of T-Mobile USA from Deutsche Telekom AG, a $39 billion deal.

The deal would vault No. 2 ranked AT&T into the leading position in the U.S. wireless market. The current industry leader is Verizon Wireless, a venture of Verizon Communications Inc and Vodafone Group Plc. Sprint, the No. 3 U.S. carrier, has also sued to stop the deal. T-Mobile is the No. 4 operator.

In addition to concerns about market concentration, the government believes that the loss of T-Mobile could push up wireless prices since T-Mobile generally costs less than other carriers.

AT&T argues the deal will accelerate its expansion of high-speed wireless service to nearly all Americans.

Other wireless carriers have also filed suit to stop the deal.

The cases are USA v. AT&T, T-Mobile USA Inc and Deutsche Telekom AG, case No. 11-1560; Sprint Nextel Corp v. AT&T Inc et al, No. 11-1600; and Cellular South v. AT&T, No. 11-1690. The three challenges are all before the U.S. District Court for the District of Columbia.

(Reporting by Diane Bartz; editing by Bob Burgdorfer)