BANGALORE/CHICAGO, Jan. 6 (Reuters) - US regional airline operator Mesa Air Group Inc. filed for bankruptcy protection on Tuesday, and said it would trim its oversized fleet and emerge as a stronger company.

Mesa has 130 planes -- about 52 of them not in use -- and said in court papers it plans to retire 25 others that it does not need.

Mesa said the downsizing will eliminate significant costs associated with retaining, maintaining and storing excess aircraft.

''Our company has ample liquidity to support itself during this process and we are confident we will emerge from Chapter 11 an even stronger operation,'' Jonathan Ornstein, Mesa chief executive, said in a statement.

Mesa filed for Chapter 11 protection in US Bankruptcy Court, Southern District of New York.

Mesa provides regional service for US Airways Group Inc., Delta Air Lines and other carriers, and had been trying to shore up its finances while riding out volatile fuel prices and a drop in travel demand.

The company, which employs about 3,400 people, said it would continue to operate as normal during the restructuring.

Mesa did not announce any job cuts on Tuesday.

In court papers, Mesa listed assets of $975 million and liabilities of $869 million as of Sept. 30. The company offered no forecast on when it expected to emerge from bankruptcy.

''It's fundamentally a function of the aircraft lessors and how willing they are to negotiate terms and conditions on the aircraft, I think will ultimately establish how successful this bankruptcy is in terms of speed and scope,'' said airline consultant Doug Abbey.

Mesa's Hawaiian inter-island, low-cost airline joint venture, go!-Mokulele, is not part of the filing and will continue to operate its full flight schedule, the company said.

Mesa also said the bankruptcy protection would help it reach a more ''timely conclusion'' in its litigation with Delta.