A Ryanair boarding attendant was left in tears after being heckled by an angry airline passenger at Brussels Airport.

The irate customer’s rant can been heard in the mobile phone footage, which has been shared to YouTube and has been viewed more than 500,000 times.

In the video, the attendant, whom the passenger accuses of being "racist," calmly warns the man she will call security if he continues his outburst.

He is then heard saying: “Ryanair check-in lady… Being a complete, total… what are you being? What are you being right now?

“You tell me I have to pay 50 euros for a flight I’m already checked in on.

“I told you I didn’t come through the departure hall because I came on a connecting flight so I have to come directly here.”

The man continues ranting until the woman begins to cry.

When fellow passengers attempt to console her, the man accuses her of having an “emotional breakdown.”

A fellow passenger steps in and says: “Sir, stop harassing her now.”

But the irate passenger tells him to “sit down, fatso. You need a break, you donut-eating bald piece of c***.”

A caption written alongside the video posted on YouTube reads: “Is it because I am ‘black’? Mob tendencies by Europeans against dark skinned foreigners, especially so called ‘blacks’ are alive and well as evidenced by this video.”

The rude passenger has been slammed online.

“Just a suggestion, you probably shouldn’t have the argument ‘Is this because of my physical appearance?!’ and then lash out at someone with ‘Hey, baldy, sit down old man!’ Even if they were at fault,” wrote on commenter.

Another said: “You are a really horrible person and you should be ashamed of yourself. F*** you.”

A Ryanair spokesperson said: “Our handling agent at Brussels Airport, Aviapartner, is looking into this matter. We will not tolerate unruly or disruptive behavior at any time.”

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H/T Irish Post