WASHINGTON (Reuters) - A U.S. appeals court on Friday blocked health insurer Anthem Inc's ANTM.N bid to merge with Cigna CI.N, upholding a lower court's decision that the $54 billion deal should not be allowed because it would lead to higher prices for healthcare.

The office building of health insurer Anthem is seen in Los Angeles, California February 5, 2015. REUTERS/Gus Ruelas

The ruling will probably kill the proposed merger, which was opposed by the U.S. Justice Department, 11 states and a District Court judge after consumers, medical professionals and others objected to it. In the end, Cigna itself tried to back out.

Still, Anthem and Cigna have the option of trying to save the deal by asking the appeals court to re-consider the case or appealing straight to the U.S. Supreme Court.

Shares of Cigna closed Friday at $156.37, up 0.1 percent, while Anthem shares ended at $177.89, down 0.2 percent.

Anthem's purchase of Cigna would create the largest U.S. health insurer. Rivals Aetna Inc AET.N and Humana Inc HUM.N had also sought to merge but that deal collapsed this year amid opposition from the federal government and states.

Insurers made the deals as they adjusted to new pressures from the insurance overhaul of Obamacare, officially known as the Affordable Care Act. They now face the potential for another remaking of the industry, though the exact changes are unclear because of Republican disagreements over how to repeal and replace Obamacare.

Anthem, said in a statement late Friday that it was disappointed by the appeals court’s decision. “We are committed to completing the transaction and are currently reviewing the opinion and will carefully evaluate our options,” the company said in a statement.

In a split decision, the U.S. Court of Appeals for the D.C. Circuit disagreed with Anthem’s contention that the Justice Department and lower court improperly rejected its assertions that the deal would lead to billions of dollars in medical savings.

“Anthem has not explained why these projected savings would even exist,” Judge Judith Rogers wrote in the opinion. “The record is clear that Anthem, unlike Cigna, has already achieved whatever economies of scale are available.”

In a dissent, Judge Brett Kavanaugh argued that the merger would benefit the biggest customers, mainly large companies with employees in many states. Kavanaugh argued that a combined Anthem/Cigna would require higher payments to manage the accounts but that would be offset by better negotiated rates paid to providers.

Kavanaugh, however, noted that the deal could be stopped based on monopsony arguments that the new company would have too much heft in negotiating with doctors and hospitals.

Anthem, a member of the Blue Cross Blue Shield Association, is the second biggest seller of medical insurance to big U.S. companies. Cigna is in third place.

Bill Baer, the former head of the Justice Department’s Antitrust Division who had made the decision to challenge both insurance mergers, said in an email that the ruling on the Anthem/Cigna deal “is a ringing endorsement of the importance of competition in health insurance markets.”

The Justice Department, now under President Donald Trump, also said that it was pleased by the decision.

Eric Schneiderman, attorney general of New York, which was among the states that had opposed the deal, also said he was pleased with the ruling.

“This is a red letter day for consumers,” said David Balto, an antitrust lawyer who opposed the deal.

In another obstacle, Anthem and Cigna have been at loggerheads for months and are suing each other. Cigna has sought to abandon the merger and force Anthem to pay a $1.85 billion breakup fee while Anthem filed a lawsuit to force its smaller rival to go through with the combination.