British airline Virgin Atlantic said it was investigating a reported incident on a recent flight from London to Shanghai in which a Chinese woman said she was abused by a fellow passenger in racist and vitriolic language and then ignored by a flight attendant.

The report of the incident went viral on Chinese social media. By Friday, about 16 million users had followed the issue on Weibo, the Chinese version of Twitter.

As of 7 pm on Friday, Virgin Atlantic's Facebook account was filled with comments from Chinese users demanding an apology.

Carly O'Donnell, a spokesperson for Virgin Atlantic, said in the statement on Friday: "We deeply regret the unpleasant experience our customer had on this flight. We have fully investigated this incident ... which resulted in both individuals becoming upset and distressed. ... We would like to reiterate that Virgin Atlantic takes a zero tolerance approach to racism."

Richard Branson, founder of the carrier, tweeted: "Really sorry to hear about an alleged incident on flight VS250. We do not tolerate abuse and Virgin Atlantic are investigating."

In her post on Chinese social media, Chinese passenger Liu Wei claimed a Caucasian male passenger insulted her after boarding the flight VS250 on March 1.

"He kept saying the 'F' word with his finger pointing at me when I asked him to apologize," Liu said in her post.

Liu said the flight attendants did not blame the man, but instead said she had to stop arguing or get off the plane.

Yan Xiaomian, a graduate student in East China Normal University, who sat near Liu on the plane, witnessed the incident.

"The Caucasian man was scary and emotional," Yan said.

Other passengers, including a Caucasian couple, reportedly stood up for Liu, but were threatened by the man.

Yan said Liu tried to talk to the attendants for an explanation and resolution, but didn't get helpful response.

"Eventually, a Chinese flight attendant helped Liu move to another cabin, and that was already more than two hours after the incident," said Yan.

The carrier said it is continuing its investigation of the incident.

Contact the writers at yandongjie@chinadaily.com.cn and wangmingjie@chinadaily.com.cn