The sales war between two supermarkets in Wolverhampton took a bizarre twist after Asda customers were targeted by a leaflet urging them to switch their allegiance.
The flyers, which were left on the windscreens of a number of cars using the Asda store in Jack Hayward Way, branded Asda products as 'rubbish', and urged people to shop at the city's new £60 million Sainsbury's instead.
Asda contacted Sainsbury's to complain about underhand tricks it believed was being used by its rival.
However, Sainsbury's denied any involvement in the leaflet campaign, and said there was no dirty tricks campaign going on.
The leaflets, which carried the Sainsbury's logo, said: "Still buying rubbish? Change supermarkets! Visit the brand new, multi-million pound mega store and petrol station... Sainsbury's, Chapel Ash, Wolverhampton. Petrol £1.299p per litre, diesel £1.339 per litre."
One customer posted a picture of the leaflet on Sainsbury's Facebook page, and said: "I am absolutely disgusted that Sainsbury's has used such underhand tactics.
"I found this under my car window screen wiper as I left my local Asda store.
"It is a shame that your colleagues had to go to such lengths."
Another Asda customer added: "Does this imply that if we don't shop at Sainsbury's we eat rubbish? A bit of a low flyer."
An Asda spokeswoman hit out at the leaflets, adding that its own fuel was cheaper anyway.
“We’re pretty unimpressed that our customers were treated so rudely by Sainsbury’s and a bit confused as to why they would go to so much effort to promote to our value savvy shoppers the fact Sainsbury’s fuel is more expensive that Asda.”
However a Sainsbury's spokeswoman denied any involvement with the leaflet.
"This is not from Sainsbury's and not something we would ever do."
Sainsbury's opened its long-awaited new store in Raglan Street earlier this month.
Hundreds of people queued up to be among the first to get a glimpse inside the new store, which has been more than 10 years in the making.
A total of 340 new jobs have been created at the store, with 192 workers moving from its now-closed store in St George's Parade.
The 72,000 sq ft store includes 700 parking spaces, an in-store cafe, recycling centre and gym, and is said to be the second largest in the West Midlands.
Work on the scheme was delayed after the company became locked in a battle with Tesco over which chain would develop the site.