DELTA Air Lines has completed its US$2.8-billion acquisition of Northwest Airlines, creating the world's biggest carrier.

Delta and Northwest closed the deal on Wednesday just hours after the Justice Department said it had no anti-trust objections.

The company will keep Delta's name, Atlanta headquarters, and CEO Richard Anderson, who used to run Northwest. Delta executives said travelers would see no differences right away. New uniforms would be phased in next year, and Northwest's fleet with its signature red tail would be repainted over the next two years, the companies said.

"I will tell you from a customer perspective and a frequent-flier perspective it is business as usual," Anderson said.

The combined airline would carry more traffic than either Air France-KLM (now the world's largest) or American Airlines, the biggest United States carrier. But anti-trust regulators rejected worries that the new Delta would hurt consumers, or competition.

Federal regulators wrote in a statement that "the proposed merger between Delta and Northwest is likely to produce substantial and credible efficiencies that will benefit US consumers and is not likely to substantially lessen competition."

It said other carriers offer flights on most of the routes where Delta and Northwest compete with each other. The Justice Department also said consumers should benefit from savings on expenses for airport operations, technology, and suppliers. The companies have said they can cut US$2 billion a year in expenses once they combine.

The decision caps a six-month Justice Department investigation, which was closed without objection to the deal from the department.

Also on Wednesday, an attorney for 28 air travelers who had sued to block the deal said the case had been settled. The attorney, Joseph Alioto, declined to release terms, which he said was worked out last Friday and finalized over the past few days.

Kevin Mitchell, chairman of the Business Travel Coalition, said the merger would mean higher fares and fewer connections between mid-size cities and business centers. He was concerned about an enlarged Delta and other possible airline combinations and joint ventures.

Anti-trust approval was announced about an hour before the markets closed. Delta shares closed down 17 cents at US$7.99, and Northwest shares rose 13 cents to close at US$9.90.