Seattle-based Alaska Airlines says it is investigating a report by the sister of Facebook CEO Mark Zuckerberg that a fellow passenger made highly sexual comments to her and that the flight crew allegedly knew about the passenger's history of this and blew it off when she complained.

Former Facebook executive Randi Zuckerberg posted on Twitter a letter she wrote to three Alaska executives including CEO Brad Tilden in which she said she was made uncomfortable by a fellow passenger in first class on a flight from Los Angeles to Mazatlan.

Zuckerberg said the man made "explicit, lewd, and highly offensive sexual comments." Among other things, she said the man was rating women's bodies as they were boarding and asking if she fantasized about the woman she was traveling with on business.

"When I brought it to the flight attendants' attention, their response was that this guy was a frequent Alaska Airlines traveler on this exact route, and they have had to talk to him about his behavior in the past, but oh well, don't take it personally, this guy just doesn't have a filter," Zuckerberg wrote.

She added that when the attendants came by, they asked the man "Are you behaving today?"

Zuckerberg said the attendants offered to reseat her to a middle seat in the back of the plane. She declined, wondering why she should be the one to move. She also said all of this happened before the plane took off, making her wonder why the passenger wasn't removed.

She went on to say the passenger was having several drinks, and talked to her about the recent wave of sexual harrassment stories in the news.

"... and how 'these Millennial women just aren't willing to give some booty to get a job anymore," he allegedly said, according to Zuckerberg.

Zuckerberg said she was furious at the airline for "knowingly and willingly providing this man with a platform to harass women."

Alaska Airlines responded on Twitter Thursday night.

"What you have shared with us is very disturbing. We have launched an investigation and have revoked this passenger's travel privileges pending the outcome of that investigation. We wish to discuss this further with you. Please DM us so we can connect tonight."

Zuckerberg said two Alaska executives talked to her on the phone and said the passenger's travel privileges have been suspended as it investigates.

"I just got off the phone with two executives from @AlaskaAir who informed me that they are conducting an investigation and have temporarily suspended this passenger’s travel privileges. Thank you for taking this seriously," Zuckerberg wrote.

Andrea Schneider, Alaska Airlines vice president of People, posted the following statement on the company's website, saying the airline had "zero tolerance" for such behavior.

I am writing today to address a recent situation involving an alleged sexual harassment incident on board one of our aircraft.

This report is very disturbing. We take it extremely seriously and have launched a thorough investigation. The safety and well-being of our guests and employees is our number one priority. We want our guests to feel safe. As a company, we have zero tolerance for any type of misconduct that creates an unsafe environment for our guests and our employees.

Our aim is to create an environment where guests and employees alike feel protected and empowered, and where our guests have a safe and enjoyable travel experience.

As a company with strong values and a deep commitment to our guests and our employees, we will do our part to find solutions to a pervasive societal problem. We are driven to learn continuously, to lead, and to do the right thing.

In the weeks ahead, we will be working with guests, employees, union partners, and other leaders to review and strengthen our approach to preventing, identifying, and addressing these important issues.