A deli owner claims Spanish people have launched a "hate campaign" against his business because he had a Catalan flag on display.
Finn Nesbitt, who owns Monusk, in Newport, says several negative reviews have been written about his deli after someone criticised the flag.
He says he replaced it with the Portuguese flag moments after the first criticism.
But it hasn't stopped a series of overnight negative reviews from people Finn says have never visited the eaterie.
He said: " We've been flying the Catalan flag recently, acknowledging the large movement pushing for independence and the heavy handed response by Spanish forces.
"My wife and I visited the region recently and talked with many pro independence supporters. I believe people should have the right to self determination. I appreciate it's a complex and sensitive issue but we did not mean to cause offense and our swift response and actions illustrate this.
This co-ordinated hate campaign against us is malicious, vindictive and clearly meant to hurt our business, which to be honest it is. We'd again like to take the opportunity to apologise."
"We have spent a lot of time and money building up the social media side of our business and it has been ruined overnight because of politics in Spain. It is bizarre. These people have obviously not given any thought to the consequences for a small, independent business."
One comment said: "The worst butifarra í ever tried (sic), dirty, impolite staff. Í Will never go again. Thats absolutely not spanish food... Horrible experience."
When Finn replied: "You did not visit and wrote this because we were flying the Catalan flag. We changed this to the Portuguese flag yesterday. We are a small, independent business and your politically based review has the potential to hurt our small family business.
"I would appreciate it if you considered this."
The reviewer said: "Your flag represents hate and xenophobia against me and all my people. It doesn't have any historical meaning, just "we are rich and you are poor, we don't want to be like you" or "we are Europe, you are Africa".
"Next time think better before insulting 40 million good people. Not every independentism is the same, with the same values. So please don't insult me."
Another wrote: "The worst place in all Newport. In spite of its fantastic gay atmosphere the food is very bad. The food is from the previous day and prepared in the microwave."
Another wrote: "The tapas dind't (sic) really remind me and my boyfriend of the original Spanish tapas. A bit overpriced. Not recommending, sorry. They weren't very welcoming of Spanish people too, quite shocking for a tapas bar."
Genuine customers have left many positive reviews on the website.
One said: "We had a lovely time here last night, lovely food and people. Would recommend."
Another said: "Absolutely lovely.. supporting our new neighbourhood.. lovely food beautiful wine and amazing new bar.. Can't wait to go again. Thank you both for a lovely afternoon."
Finn added: "What I could really do with is for people to counter this deluge of negative and offensive reviews with some positivity. On both Google & Facebook if possible. Thanks so much your your help and support. All we want to do is make our community a better place. Peace, love and reconciliation - not hate."
On Sunday, hundreds of thousands who want Catalonia to remain part of Spain have rallied in Barcelona, two days after separatists voted for the wealthy region to secede.
Organisers said the goal of Sunday's march was to defend Spain's unity and reject "an unprecedented attack in the history of democracy".
Leaders of rival pro-union parties from the ruling conservatives, the pro-business liberals and the socialists joined together under the slogan "We are all Catalonia. Common sense for co-existence!"
Grassroots group Societat Civil Catalan called for those who oppose Catalonia breaking away to march at noon. Demonstrators, many waving Spanish, Catalan and European Union flags, flooded a central boulevard.
