WASHINGTON — Regional airlines report difficulty over the past year in finding enough pilots to hire, according to a government watchdog report obtained by The Associated Press, but it isn’t clear whether there is a shortage of pilots.

Researchers found “mixed evidence” of a shortage, said the Government Accountability Office. A key economic indicator supports the emergence of a shortage, but two other indicators suggest the opposite is true. Of three studies reviewed by the GAO that examine the issue, “two point to the large number of qualified pilots that exist, but may be working abroad, in the military, or in another occupation, as evidence that there is adequate supply,” the report said.

The report, obtained late Thursday, was to be released Friday.

The U.S. airline industry will need to hire 1,900 to 4,500 new pilots annually over the next 10 years due to an expected surge in retirements of pilots reaching age 65 and increased demand for air travel, the report said.

Eleven out of 12 regional airlines failed to meet their hiring targets for entry-level pilots last year, the report said. However, no major airlines were experiencing problems finding pilots. Some airline officials did express concern that service to some cities might have to be cut back if their regional partners cannot hire enoughpilots, the report said.