A United Airlines flight attendant refused to give a passenger an unopened can of Diet Coke aboard a United flight, saying the woman could use the can as a weapon, the passenger claims.

The woman, Tahera Ahmad, an interfaith chaplain at Northwestern University and prominent religious scholar, posted her story on Facebook, setting off a social media backlash Saturday morning against United Airlines. Ahmad says she was offered an open can but asked for an unopened can for sanitary reasons. The flight attendant refused, saying to do so was against airline policy.

"No Diet Coke for you," the flight attendant declared, according to Ahmad. Ahmad, who was on Flight 3504 bound for Washington, D.C., to speak at the Kids for Peace Conference, says the flight attendant then handed the man seated next to her an unopened can of beer. After seeing that, Ahmad asked for an explanation, and the flight attendant told her unopened cans can be used as weapons.

Ahmad replied that she was clearly being discriminated against, noting the unopened can of beer. Ahmad claims the flight attendant grabbed the man's beer and opened it for him and said "it's so you don't use it as a weapon." Ahmad looked to fellow passengers for some acknowledgment the flight attendant was being discriminatory. And for that, she was brought to tears. A man in the aisle next to her leaned over, Ahmad claims, and said, "You Moslem, you need to shut the f--- up. ... You know you would use it as a weapon, so shut the f--- up."

Ahmad wears a hijab, the traditional head covering of Muslim women.

It's routine on many flights for flight attendants to hand unopened beverage cans to passengers.