American Airlines parent AMR Corp (AAMRQ.PK) and US Airways Group Inc (LCC.N) said on Friday the carriers have to evaluate a potential merger.

The companies have signed a non-disclosure agreement and agreed to exchange confidential information in collaboration with AMR's Unsecured Creditors Committee, the airlines said.

American Airlines, which has been operating under Chapter 11 bankruptcy protection since November, also said in a memo to managers that it signed non-disclosure agreements with "other parties" that it did not identify.

Morningstar analyst Basili Alukos said it would be in the best interests of American and US Airways to combine, a tie-up that would create a company rivaling United Continental Holdings Inc (UAL.N) and Delta Air Lines Inc (DAL.N) in scope.

"You would have the international operations of AMR and the lower cost structure of US Airways," Alukos said.

Shares of US Airways were up 2.5 percent to $10.66 and shares of AMR were up 2.9 percent to 46.5 cents in morning trading.

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