A duty-free discount event at Heathrow has resulted in Chinese passengers threatening to boycott the airport after they were allegedly required to spend hundreds of pounds more than customers from other nationalities to benefit.

According to a number of shoppers, some Chinese travellers were required to spend as much as £1,000, or even more, to enjoy VIP discount vouchers offer from World Duty Free . They alleged that shoppers from other countries were able to spend as little as £79 to get the same vouchers, and claimed this was racial discrimination.

Numerous reviews and comments have since been posted on Heathrow Airport's Facebook page by Chinese customers who discovered the "unfair" promotion.

Eileen Xiao, a student at Coventry University, said she was "so upset and angry" by the "racial discrimination". "We need an explanation," she added, in a post in which she shared screenshots of three reviews from Chinese people making the claims. The allegations were also made in Facebook posts on the Heathrow page, on Twitter, and on Chinese social media site Weibo.

One of the reviews said: "This is discrimination and should not be tolerated in any means. We should support by boycotting purchas[ing] any products from LHR unless LHR provides a proper resolution.

"I will personally not [be] buying anything from Heathrow any more and I will not choose LHR as a transfer point. Feel sick about it." The reviews section of the Heathrow Airport Facebook page now appears to have been disabled.

In a Facebook post which screenshotted a Chinese explanation of the issue and a photo of the vouchers in question, Steven Li wrote: "I hope all Chinese do not go shopping at Heathrow Airport World Duty Free anymore. They treat us like idiots."

A Heathrow spokesperson told the BBC: "We have been made aware of this offer which we find unacceptable. We are currently working with our commercial partner to understand how this happened and ensure it does not happen again." IBTimes UK has contacted Heathrow for further comment.

World Duty Free, which ran the discount event, posted an apologetic statement on Twitter. It said: "As a global company we are committed to treating all our customers with respect and in a consistent and fair way. We would like to offer our sincere apologies to our customers who were in any way made to feel this was not the case.

"The VIP programme is designed to reward customers - on top of our normal promotions - at certain points of the year by offering an attractive incentive on a second purchase. The implementation of this promotion has been confusing which we sincerely regret.

"After close self-examination and having made further investigations, we have taken urgent steps to correct the implementation of this promotion going forward.

"We have comprehensively re-briefed our staff in our stores to ensure that the promotion is clear. This offer applies regardless of the destination customers are flying to."

The statement was posted in both Chinese and English, but some Twitter users pointed out the "double standard" that the Chinese were not mentioned once in the English version. One Chinese customer wrote: "Be aware that however you treat Chinese customers, Chinese customers will never forget."