Oh boy. United Airlines is trending on Weibo, China's version of Twitter -- but it's not pretty.

On Monday, United forcibly removed an Asian man from a Chicago-Louisville flight. In disturbing footage, the security staff are seen struggling with the passenger, before he is removed from his seat and dragged down the aisle with a bloodied mouth.

The incident was top on Weibo on Tuesday, with the hashtag #美联航强制乘客下机# , or "United forces passenger off plane."

Over 180 million users have engaged with the trending topic, and have collectively posted 890,000 comments.

The outrage is China appears to have come from a media quote from a passenger onboard the flight, Tyler Bridges.

"He said, more or less, 'I'm being selected because I'm Chinese'," Bridges had told the Washington Post.

United has said that the four passengers selected to disembark were picked at random. It's also denied accusations that the man was picked because of his race.

Despite this, the translated comment has sparked fresh outrage on Weibo, where people are boycotting the airline and cutting up their membership cards.

This netizen says: "Boycotting starts with me."

SeanHasToStudyMore: "The official response feels so patronising. I've canceled my mileage card. @StarAlliance @UnitedAirlines"

dee__W: "I've had enough -- now's the time. I rather pay more money than get on a UA flight."

TravellingKid, who lives in the US: "I can't believe this has happened on my doorstep. My friends have immediately canceled our card with United."

The race discussion has also blown up.

Says Joe Wong, a Chinese-born comedian: "I'd love to give this passenger a 'like' -- many Chinese feel that they've been discriminated but never say it out loud because they are afraid of losing face. So the Western mainstream media and the public don't feel as if racism against Asians is a thing."

TheWindBlows: "If the doctor wasn't Chinese I might not have said a thing...No matter where you're from, if you're Chinese, our fates are tied together. We have to fight for our own future!"

MeiMeidiShouZi: "I feel really pissed. There's so many people, why make a 69-year-old Chinese doctor who needs to work the next day disembark? And you beat him up and drag him out...shocking. And your computers just so happened to choose an Asian? It's suspect!"

DuanLiao: "I think he's Japanese."AquariusZhuDaKe: "No matter the nationality, as an airline, this is not the way to treat passengers."

____RRRRRRR: "This is an attack on the human rights of Asians; can you still standby and watch as this guy is attacked?"

China is a key market for the airline. United operates several non-stop U.S.-China flights to cities like Shanghai, Beijing and Chengdu. It designated new planes for its Hong Kong-San Francisco route early March, and claims to operate "more nonstop U.S.-China flights, and to more cities in China, than any other airline."