American Airlines stepped up a verbal battle with Qatar Airways Ltd., assailing what the U.S. company said were "sexist and ageist" comments by the Mideast carrier's chief executive officer.

The rebuke was triggered after Qatar Airways CEO Akbar Al Baker said at a Dublin event that the average age of his cabin crews is 26 and that "you are always being served by grandmothers" on U.S. carriers.

The remarks were "incredibly offensive," Jill Surdek, vice president of flight service for American Airlines Group Inc., said in a message to employees Tuesday. "It was both sexist and ageist at the same time."

The exchange fueled a spat between the two carriers, which have been trading barbs since American disclosed last month that Qatar Airways had expressed interest in buying about 10 percent of the U.S. carrier. American CEO Doug Parker has called Qatar Airways' intention "puzzling at best and concerning at worst." Al Baker last week responded that his counterpart was "frightened" by the proposed investment.

Parker and the CEOs at Delta Air Lines Inc. and United Continental Holdings Inc. have called for diplomatic talks on whether state-owned Qatar Airways and fellow Persian Gulf carriers Emirates and Etihad Airways PJSC have used government aid to expand unfairly in the U.S.

'New Low'

The Partnership for Open & Fair Skies, a coalition of the three U.S. airlines, on Tuesday called Al Baker's latest remarks "misogynistic and demeaning." Labor groups weighed in as well, with the Air Line Pilots Association saying he had "sunk to a new low." Dennis Tajer, a spokesman for the Allied Pilots Association at American, called the comments "insulting, disrespectful and childish."

"Qatar's actions and words exhibit a scorched-Earth business mentality," Tajer said.

Bob Ross, president of the Association of Professional Flight Attendants, also criticized Al Baker's remarks and defended members at American Airlines as "well-seasoned and highly trained professionals." The Southwest Airlines Pilots' Association said the comments were "reflective of a pattern of discrimination and deceit" by Qatar Airways.

"It is time for our government to stand up to these discriminatory actions and stand up for U.S. aviation," the Southwest union said in a statement.

Qatar Airways didn't respond to requests for comment.

The Mideast carrier would have to gain approval from American's directors to exceed a 4.75 percent stake in the Fort Worth, Texas-based airline. Al Baker has said he doesn't plan to seek more than 10 percent, nor will he attempt to gain a board seat.

Qatar Airways and American are partners in the Oneworld global alliance. Qatar owns 25 percent of British Airways parent IAG SA, which also operates a joint venture with American.