By Karen Jacobs

Feb 1 (Reuters) - AMR Corp has asked a bankruptcy judge for another extension of its exclusive period to file a plan to exit bankruptcy.

In a filing on Thursday, the carrier and its unsecured creditors committee asked the U.S. Bankruptcy Court to extend the period during which creditors cannot pursue their own restructuring plans for the airline to April 15. That replaced a January request to extend the time to April 1.

Currently, American has until March 11 to file its reorganization plan.

AMR filed for Chapter 11 protection in November 2011 citing high labor costs.

The company is discussing final details of a potential merger with US Airways Group, people familiar with the matter have said. A combination of American and US Air would form the world's biggest airline.

"American has made significant progress in its restructuring," spokesman Sean Collins said in a statement emailed to Reuters on Friday.

"This work, while progressing well, takes time, and American and the unsecured creditors' committee believe that the proposed extension to April 15, 2013, is appropriate for this process to continue in an orderly and efficient manner."

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