MORRISONS has been accused of attempting to kill off Liskeard's shops as the superstore applies for retrospective planning permission for an outdoor garden centre.
It began selling plants under a canopy in March and has now applied to Cornwall Council for consent should it wish to do so again.
Gavin Davies, chairman of Liskeard Chamber of Commerce, said trade was being pulled out of the town, away from independent shops.
"These sort of applications will only go to impede the amazing work being done by multiple organisations to improve the town," he said.
"This isn't simply giving more options to existing product ranges, but allowing Morrisons to move into new product sectors.
"We already have a well stocked garden centre and multiple other shops in the town offering these kinds of products. There's no need to put people's jobs at risk in these difficult times."
A Morrisons spokeswoman said the garden centre was temporary and had now shut. "The garden centre was an extension of our usual offering," she said. "We had great feedback from customers, so the application will be progressed in case we want to use the space again."
Jenny Deacon, the chamber's membership secretary, said she was appalled to see Morrisons selling plants and it was another huge step towards killing the town.
"To now find out that they didn't have planning permission is appalling," she said.
"How can a huge concern like Morrisons think they can flout the rules like this?"
Jane Pascoe, who runs Seasons Bistro in the town centre, questioned why Morrisons had been allowed to trade without planning permission, and said a small local trader in Liskeard town centre would have had council enforcement officers "crawling all over them".
Cornwall Council's planning register records five applications on the Morrisons site since 2000.
Mrs Pascoe said: "Time after time Morrisons have put in planning applications to expand their out-of-town store and the local councillors allow it to be approved, systematically causing the closure of shops in our lovely town.
"This time, let's see if the local councillors will support the local traders and consider the implications of allowing this extra floor space."
Mrs Pascoe said she did not believe there was a need for such an expansion, as the Homebase opposite had a vast range of horticultural items.
She urged townsfolk to "please support the traders in and around Liskeard town centre. They contribute to your local economy, offer individual friendly service, work tirelessly behind the scenes and believe your town is worth fighting for."