Shoppers at the supermarket have threatened to boycott Heinz products after spotting the price of a small bottle at Asda. A woman expressed her surprise on Facebook after initially believing the price tag was a mistake.

Liz Ferla posted a photograph on a popular deal-swapping group, showing large 910g bottles of Heinz ketchup on sale at her local Asda for £3.50, discounted to £4. Alongside them, 460g bottles, nearly half the size, were priced at £3.40.

The post drew more than 1,000 comments, many of them from outraged shoppers who had also noticed rising prices at their local supermarkets. The original post reads: “Went shopping at Asda today, prices skyrocketed!

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“The huge bottle of Heinz Ketchup has gone up to £3.50. But the small bottle has gone up to £3.40! Surely a mistake!”

“I don’t use it, but I liked to save the small bottle for when the grandchildren visited, but I’m afraid they’ll have to do without it in the future! I know the big bottles are cheaper, but they usually end up in the trash, I don’t visit it that often.”

Hundreds of fellow shoppers shared their disbelief in the comments section, with some threatening to boycott Heinz products altogether. One person said: “I’ve noticed all the Heinz products have shot up, it’s getting out of hand.”

One comment that drew more than 200 likes read: “Just don’t buy it… it’s the only way to stop the madness.”

A third person wrote: “Heinz is a rip off. I found Aldi’s Bramwells so much less expensive and they taste as good as!” And another said: “Asda’s own brand is just as good and a fraction of the price.”

At the time of writing, the 910g bottle of Heinz was cheaper at Asda than at all other major supermarkets. Waitrose’s costs more at £4.50. The smaller 460g bottle was more expensive at Asda, Tesco and Ocado. It was cheaper at Sainsbury’s at £2.50 and £2.90 at Co-op.