ATLANTA — Mesa Air Group Inc. says Delta Air Lines Inc. is again trying to terminate a regional flying contract with Mesa subsidiary Freedom Airlines.

Phoenix-based Mesa said yesterday that on Friday it received notification from Delta that the carrier is ending Freedom's CRJ-900 Delta Connection agreement, once again alleging Freedom failed to maintain specified operational performance, as outlined in the contract.

"Mesa strongly disputes these allegations and intends to vigorously defend its contractual rights," the company said.

Mesa, which is the parent of interisland carrier go! airlines, added that it believes the cancellation plan was driven by Delta's intention to reduce capacity and its "inability to reduce aircraft at its wholly owned Comair subsidiary without incurring significant ongoing expense."

Delta stood by its decision.

"It's more important than ever before that Delta and its Delta Connection partners meet operational and customer service levels," Delta spokeswoman Betsy Talton said.

Freedom operates seven 76-seat CRJ-900 regional jets for Delta Connection, with a further seven aircraft scheduled to enter service by May 2009.

Delta previously tried to terminate Freedom's ERJ-145 Delta Connection agreement on the grounds Freedom did not meet operational performance standards spelled out in its agreement with Delta. Mesa won a preliminary court injunction to block the move. Delta is appealing the decision.

Mesa had said the previous move, if successful, would have crippled its airline. It did not say yesterday what financial impact the termination of the CRJ-900 contract would have on Mesa. The ERJ-145 contract covers 34 50-seat aircraft.