Health officials described the move as unwarranted. The Edinburgh-based chain, Scotmid, placed advertisements in newspapers offering to accept the return of cold meats, cooked pies, bakery products and uncooked sausages bought from any of its 61 outlets across Scotland.
Only four of its supermarkets had been identified as having stocked products made by John M Barr and Sons of Wishaw, where the outbreak allegedly originated. MPs for the region said they were mystified by the decision. Dr John Reid, Labour MP for Motherwell North, said: "If 61 outlets were involved instead of four, why weren't we told before now?
"All along, we have been told that only cooked meats were involved in the outbreak. If other products could be affected, why are we being told five weeks into the outbreak? And if they aren't, then why is this supermarket chain causing unnecessary confusion all over Scotland?"
John Brown, spokesman for Scotmid, said the company was merely being cautious on behalf of its customers. "There is a lot of confusion over E. coli and we are just playing on the safe side. From the beginning, we have told our customers we would be prepared to accept the return of any goods they were worried about.
"Last week, a board meeting decided to extend that offer across all our stores and to include frozen products. After all, who knows what might be lurking at the back of the freezer?" He denied the operation may have been a public relations exercise that had backfired.
Professor Hugh Pennington, who leads the inquiry into the outbreak, is today due to present his preliminary findings to the Secretary of State for Scotland, Michael Forsyth.
Last night, the Scottish Office said there had been no new confirmed cases of E. coli poisoning since 20 December. So far, 409 people have shown symptoms of the illness, while 258 have been recorded as confirmed cases. Sixteen have died.