MANILA, Philippines-Philippine Airlines "will soon file appropriate charges" against some pilots who resigned and failed to report for work immediately after submitting their resignation letters, the flag carrier said in a statement Sunday.

"The indiscriminate resignation of PAL's A320 pilots for flying jobs abroad whose salaries PAL is unable to match is in violation of their contracts with PAL as well pertinent government regulations that require resigning pilots to give PAL six months prior notice to be able to train their replacements," the statement said.

"Most of the pilots still owe PAL the cost of their aviation school training, which run into millions of pesos per pilot," it added.

At the same time, PAL apologized to passengers inconvenienced by the disruption of several PAL flights due to lack of pilots licensed to fly its Airbus A320 airplanes.

"PAL is currently adjusting its schedules by merging some flights, upgrading aircraft to bigger types and fielding of management pilots to lessen the inconvenience to affected passengers," the statement said.

Passengers are also asked to call the PAL hotline at 855-8888 for flight updates.