Top Republicans in the House Energy and Commerce Committee want more information on why regulators are not supporting AT&T Inc's $39 billion bid for Deutsche Telekom AG's T-Mobile USA.

The Justice Department went to court last week to block the deal, and the Federal Communications Commission said it also had concerns about the deal's impact on competition.

In a letter sent to FCC Chairman Julius Genachowski and Attorney General Eric Holder on Thursday, Republican legislators requested a bipartisan briefing on what went into the decision to challenge the merger and whether the agencies considered the impact on jobs and economic growth.

Signed by House Energy and Commerce Committee Chairman Fred Upton, House Subcommittee on Communications and Technology Chairman Greg Walden and committee Chairman Emeritus Joe Barton, the letter asked for a meeting within the next two weeks.

It is clear that this is a complex transaction and it is important that government officials reserve judgment until all of the facts have come to light, the letter said.

Deputy Attorney General James Cole said at a briefing on August 31 that the merger would reduce competition in the wireless market on three levels: price, quality and innovation.

Lawmakers have no direct role in reviewing the merger that was proposed in March, but Congress, through oversight of the regulators and by holding hearings, can influence public opinion.

If approved as proposed, the merger would concentrate 80 percent of the U.S. wireless market in just two companies: AT&T/T-Mobile and Verizon Wireless, a venture of Verizon Communications Inc and Vodafone Group Plc.

AT&T argues the deal will help it provide faster service to more customers. Critics charge that less competition will increase prices and limit consumer choice.

The FCC had no comment, while DOJ could not immediately be reached for comment.

(Reporting by Jasmin Melvin; editing by Andre Grenon)