The U.S. Justice Department has a team of litigators prepared to oppose the merger of ticketing giant Ticketmaster and concert promoter Live Nation and could decide to take the deal to court, antitrust sources said on Wednesday.

The DOJ has had a litigation team preparing the case for litigation for months, one antitrust source said, adding that TheDeal.com publication was inaccurate in reporting that the Justice Department was prepared to approve the deal.

From the best we can tell, no decision has been made, said a second antitrust source. We have the impression that efforts to settle have fallen through.

Shares of both Ticketmaster and Live Nation opened higher on TheDeal.com report but later slid back somewhat on news of potential Justice Department opposition.

Ticketmaster shares were up 5.2 percent at $14.40 on Wednesday afternoon after peaking at $15.02 earlier in the session. Live Nation was up 6.6 percent at $9.97 after jumping as high as $10.28.

Live Nation is the world's largest concert promoter, while Ticketmaster is the leading ticketing group.

Neither Ticketmaster nor Live Nation had any immediate comment.

The deal has been viewed as the Obama administration's first best chance to demonstrate that it is serious about a pledge to take a tougher look at mergers.

This is such an educational moment, said Bert Foer, president of the American Antitrust Institute, which opposed the deal.

To create a single platform that goes from the talent all the way down to the fan is to create a system that has no rival. It's a really serious test case for whether the Justice Department is willing to go to litigation.

DOJ (the Justice Department) should block this merger outright, and we have every hope that they will do so, said TicketDisaster.org, a coalition of consumer groups and venue owners formed to oppose the merger.

David Balto, a former policy director at the Federal Trade Commission who works with the coalition, said the opposition to the merger was unprecedented.

Over 50 congressmen have spoke with a single voice saying this merger should be stopped, he said.

But because the companies have different areas of expertise, the deal may be a hard one to fight, said Andre Barlow, an antitrust lawyer with Doyle, Barlow and Mazard PLLC.

Politically, you wouldn't get in trouble for challenging the deal because everyone hates it, but articulating an antitrust theory is more difficult, he said.

In February, Live Nation announced plans to buy Ticketmaster Entertainment for about $400 million in stock, drawing almost immediate criticism from some U.S. politicians and artists who felt the combined group would have unrivaled power over music fans and the prices they would have to pay.

Last month, the deal got a boost when British antitrust regulators dropped objections and approved it.

(Editing by Maureen Bavdek, Lisa Von Ahn and Steve Orlofsky)