CHICAGO » A Shuttle America flight attendant "will no longer serve United customers" following an investigation into a Muslim chaplain’s complaint of discriminatory treatment during a flight, an airline spokesman said Wednesday.

In an email to The Associated Press, United spokesman Charles Hobart said the airline "does not tolerate behavior that is discriminatory — or that appears to be discriminatory — against our customers or employees."

The statement came five days after Northwestern University chaplain Tahera Ahmad said a flight attendant declined her request for an unopened can of Diet Coke because it could be used as a weapon. The flight was operated by Shuttle America for United.

Ahmad’s description of the incident on her Facebook page Friday led to news articles and a Twitter campaign supporting her.

Ahmad said during a flight Friday from Chicago to Washington, D.C., a flight attendant gave another passenger an unopened beer can but told her that people weren’t allowed to have unopened cans because they could be used as weapons.

"She said, ‘You would use it as a weapon.’ At that point I felt she crossed a line," Ahmad told the AP. She asked other passengers if they saw what happened, and one man swore at her, Ahmad said.

She was wearing the Muslim headscarf known as the hijab.

United previously issued a statement that described the incident as "a misunderstanding regarding a can of diet soda." The airline sharpened its stance as Ahmad and the Chicago chapter of the Council on American-Islamic Relations prepared Wednesday for a news conference in Chicago.

The new United statement also followed a letter from Northwestern University President Morton Schapiro to United CEO Jeff Smisek requesting a formal apology and "assurances that United will train its staff so that she and others are never again subjected to such discrimination on a United flight."

Hobart said Wednesday that United’s "customer-facing employees undergo annual and recurrent customer service training, which includes lessons in cultural awareness." He said United will "continue to work with all of our partners" on cultural awareness.

"While United did not operate the flight, Ms. Ahmad was our customer and we apologize to her for what occurred on the flight," Hobart said.