A Consumer Affairs survey has highlighted a large discrepancy in the price of groceries across Tasmania, but supermarket chiefs have questioned the accuracy of the test after errors in the figures forced the government to issue a correction.

Peter Patmore, Consumer Affairs Minister, stood by the survey’s conclusions but admitted that in order to give an unbiased result it “will continue into the future”. The survey was conducted by the government, in conjunction with the Tasmanian Pensioners Union and Anglicare representatives.

The survey found that consumers at Woolworths Kingston paid on average A$11 (US$5.8) more for the same basket of 25 grocery items than at Woolworths Sorell, but the chain’s managing director Michael Kent argued: “They have made a blue… the price difference does not make sense.”

Kent pointed out that elsewhere, the survey claims to have found a similar price discrepancy at Woolworths Glenorchy Central store and Woolworths Glenorchy, but these are actually the same store.

“What else did they get wrong?” he asked: “They need to get this type of thing right and I’m happy to help them […] We have got nothing to hide.”

Kent added that Woolworths’ prices are generally the same throughout Tasmania because they are listed in a central computer system. Price fluctuations only occur in response to changes at a nearby competitor.