A burger van owner has sparked a social media uproar after posting an expletive-filled rant on the business’ Facebook page after a customer complained.

A female patron accused New Zealand burger bar, Ekim Burger, of giving her son food poisoning, and wrote a letter to owner Mike Duffy.

But Mr Duffy hit back and posted a screengrab of the private message from the Wellington woman, who said she had dined at the restaurant with her son, who then vomited after their meal.

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The woman went on to say the burger was the only thing he had eaten that day, adding “so we assume it was the burger”.

Mr Duffy then took to his Facebook page and wrote a long rant in response.

The unedited post reads: “Almost 20 years in this f****ng industry and never had a person who ate what I cook get sick from it.”

Mike Duffy posing in front of his Ekim caravan. Photo: Twitter

“Don’t point fingers unless you know for sure. specialy when it’s something as serious as a potential food poisoning out break,” Mr Duffy wrote.

“These are as far as I’m concernd very serious a harsh accusation if you’re offend by my tone or the messsge, good!

“God only knows enough of you have offend me over the years with your ignorance and lack of respect for the hard working individuals that cook your meals when you don’t.”

Mr Duffy then went on to describe the type of clientele he had to deal with each day.

“Plenty of pi**ed-up office jocks pulling the ‘I got food poisoning’ call after going home way to drunk from a staff Christmas party with someone who they shouldn’t have,” he wrote.

“Loads of middle class no idea house wives completely out of their league complaining that their wine glass should have more in it. Dozens of too drunk to drive but gonna anyway cos they can lawyers with no regard for the position they put you in as the license holder by driving home.

“100000s of eggs on Sunday mornings when no one, least of all the other staff wants to hear some little sh** kid banging his or her fork on the wooden table only to be released from its chair to f*** up the morning of other diners. So its dimwitted parents can talk about what s*** the service is even though they’d never tip no matter how good it was.

“This is the world through the eyes of a somewhat tired of being pestered about s*** that dont matter to me grill cook”.

Mr Duffy was unapologetic about his rant which he said was inspired by “a creeping culture of rudeness and entitlement among hospitality patrons”.

“It’s common courtesy, and it’s not common anymore,” Mr Duffy told stuff.co.nz.

Mr Duffy claimed his decision to post a private message was justified on the grounds that nothing on the internet was confidential, and that if the woman did not want the message to potentially go public she should not have sent it.

Burger patrons and Wellington residents took to social media in response to the rant.

If you’ve somehow missed it then why not check out the much beloved Ekim Burgers self destructing on Facebook: http://t.co/F8AahDcS0r

— Jay Harvie (@JayHarvie) April 30, 2015

How to NOT social media 101 http://t.co/bQ1HokqIvD

— Emily (@emmymclean27) April 30, 2015